How to turn into a equation?

[vivitheparakitty]

The three questions below are to help me to make an equation/expression...I don't know how, someone teach me! I know the answers but I have to do it the algebra way.
1. 840 stickers were given to 42 children. 2/3 of the children were boys, and each of them received the same number of stickers. Each girl received twice as many stickers as each boy. How many stickers did each girl receive?
2. Mrs. Suarex bought 3 pairs of jeans and 5 shirts for $441. If each pair of jean cost 2/3 as much as each shirt,
(a) what was the price of each pair of jeans?
(b) what was the price of each shirt?
3. Eric collected 1 1/3 times as many beads as Malik in the beginning. If Eric collected 48 more beads and Malik collected 13 more beads, Eric would have twice as many beads as Malik. How many beads did they collect altogether in the beginning?

 

[Steven G]

1) There are 840 stickers to be given to 42 children

2/3 of the children are boys. This says that The Number of Boys is 2/3 of The Children. is means = and of means * (ie to multiply)
Let B = the number of boys.
So B = (2/3)*42 = 28.

The number of girls is then 42-14= 28.

Let x = number of stickers each boy gets.
Then 2x = number of stickers each girl gets.

So 28*x + 14*2x = 840
That is 28x+ 28x =56x = 840. Solve for 2x.

I did most of the problem for you so you can have an example to work from.

The rest you have to show some effort. We are here to give you hints along the way, not to do the problems for you. Please post back.

 

[JeffM]

To USE algebra to solve problems, you need to be able to set up equations. So even if you can solve a problem without algebra, that will never help you learn how to use algebra.

One of the main uses of algebra is to provide a way to find unknown quantities. The first step is to "name" what is unknown with a letter.

[MATH]x = \text {number of stickers given to EACH boy.}[/MATH]
[MATH]y = \text {number of stickers given to EACH girl.}[/MATH]
[MATH]b = \text {number of boys.}[/MATH]
[MATH]g = \text {number of girls.}[/MATH]
You are just identifying each quantity that you do not know and giving it a name.

In general, to find a specific number of unknown quantities, you need to know AT LEAST THE SAME NUMBER of quantitative facts about them. So start looking.

[MATH]b + g = 42.[/MATH]
[MATH]\dfrac{2}{3} * 42 = b.[/MATH]
[MATH]y = 2x.[/MATH]
[MATH]b * x + g * y = 840.[/MATH]
Do you see where those numeric relationships came from? That is actually the hardest part. Now you have the mechanical part: solve the system of equations.

[MATH]\dfrac{2}{3} * 42 = b \implies b = WHAT?[/MATH]
So what is g?

But that means you can fill in b and g with actual numbers in the equation

bx + gy = 840.

WHAT NEXT?

 

[vivitheparakitty]

1) There are 840 stickers to be given to 42 children

2/3 of the children are boys. This says that The Number of Boys is 2/3 of The Children. is means = and of means * (ie to multiply)
Let B = the number of boys.
So B = (2/3)*42 = 28.

The number of girls is then 42-14= 28.

Let x = number of stickers each boy gets.
Then 2x = number of stickers each girl gets.

So 28*x + 14*2x = 840
That is 28x+ 28x =56x = 840. Solve for 2x.

I did most of the problem for you so you can have an example to work from.

The rest you have to show some effort. We are here to give you hints along the way, not to do the problems for you. Please post back.

I got all the answers using an algebric expression! Thank you so much

 

[HallsofIvy]

1) There are 840 stickers to be given to 42 children

2/3 of the children are boys. This says that The Number of Boys is 2/3 of The Children. is means = and of means * (ie to multiply)
Let B = the number of boys.
So B = (2/3)*42 = 28.

The number of girls is then 42-14= 28.

Surely you mean
"The number of girls is then 42- 28= 14"!

Let x = number of stickers each boy gets.
Then 2x = number of stickers each girl gets.

So 28*x + 14*2x = 840
That is 28x+ 28x =56x = 840. Solve for 2x.

I did most of the problem for you so you can have an example to work from.

The rest you have to show some effort. We are here to give you hints along the way, not to do the problems for you. Please post back.