Algebra Representation: "Susan wanted to purchase some dog treats for her new puppy...."

[joshdal9]

Susan wanted to purchase some dog treats for her new puppy. She buys 12 biscuits for $1.50 each and 15 chews for 80 cents each. How much did she spend?
Show this algebraically

 

[stapel]

Susan wanted to purchase some dog treats for her new puppy. She buys 12 biscuits for $1.50 each and 15 chews for 80 cents each. How much did she spend?
Show this algebraically

Okay; you've provided the text of the exercise. Now what?

Kindly please re-read the "Read Before Posting" message, and reply with the requested information, starting with what your book means by "show[ing] this algebraically" (since the actual work is merely two multiplications and one addition). Thank you!

Eliz.

 

[The Highlander]

Susan wanted to purchase some dog treats for her new puppy. She buys 12 biscuits for $1.50 each and 15 chews for 80 cents each. How much did she spend?
Show this algebraically

In Algebra we use letters to represent variables (usually quantities that can change but are sometimes given as a fixed number).
So the first thing you must do is assign (give a letter to) each of the things you are dealing with.

If I wanted to find out how much I had spent on buying eggs (for example) I would multiply the number of eggs I bought by the price of each egg.

I could start by assigning letters to these things like this:-

T = Total Expenditure (How much I spent.)
P = Price of 1 egg
Q = Number of eggs purchased

Then I could write a simple equation...

T = P × Q

That is what your question is asking you to do, however, I suspect you might also be expected to solve it too as the question does (specifically) say: "How much did she spend?" as well as: "Show this algebraically".

To solve my equation I would follow these steps...

1. Start by writing down the equation .​

2. Then List all the terms I know the value of. (My "knowns")​

3. Re-write my equation substituting those values into it (by replacing the letters with given values)​

and​

4. Evaluate the unknown quantity (to get my answer).​

Thus...

T = P × Q      P = 30p (Price of one egg.)
              Q = 24 (I bought two dozen.)
So...
T = 30 × 24 ⇒ T = 720


So I spent 720p or £7.20 buying my eggs.

I your case I would start by (similarly) saying...

T = Total Expenditure (How much Susan spent.)
P_B = Price of 1 biscuit ($1.50)
Q_B = Number of biscuits Susan bought (12)
P_C = Price of 1 Chew (80¢*)
and
Q_C = Number of Chews Susan bought (15)

then go on to write an equation for T using the terms P_B, Q_B, P_C & Q_C (similarly to what I did above) and then proceed to solve it for T to get an answer for how much Susan actually spent in the same fashion as I did above.

Please now show us your attempt at this.

NB: *You should change the Chew price into dollars (or that of biscuits into cents) so you are only using one currency unit.
To get a variable 'name' (like P_B you type PB, then highlight the "B" and click on "X₁" from the "Formatting Menu" (above your post). You will see "X₁" when you click on the three dots (⋮) at the far right of the Menus.

Hope that helps. ?

 

[Dr.Peterson]

Susan wanted to purchase some dog treats for her new puppy. She buys 12 biscuits for $1.50 each and 15 chews for 80 cents each. How much did she spend?
Show this algebraically

It's possible that they just want you to write a single expression using these four numbers, and then evaluate it. Or they might want variables of some sort (not necessarily as complicated as Highlander's).

Can you show examples of what they have done "algebraically" for a different question, so we can see what they might mean?