Linear equations- Problem solving

[Guest]

I only need help on these 2 problems. I just started class and I'm in a Pre-Ap class.

#76. It takes you 30 minutes to rake the leaves in your yard and it takes your brother 45 minutes. How long does it take the two of you to rake the leaves when working together?

#78. A cylindrical thermos with an inside diameter of 2 1/2 inches is filled with liquid to a height of 9 inches. If the liquid is poured into a cylindrical travel mug with an inside diameter of 3 1/2 inches, what will be the height h of the liquid?

 

[Deleted member 4993]

I only need help on these 2 problems. I just started class and I'm in a Pre-Ap class.

#76. It takes you 30 minutes to rake the leaves in your yard and it takes your brother 45 minutes. How long does it take the two of you to rake the leaves when working together?

Hint:

What fraction of the yard can you rake in 1 minute?

What fraction of the yard can your brother rake in 1 minute?

What fraction of the yard can (you+your brother) rake in 1 minute?

#78. A cylindrical thermos with an inside diameter of 2 1/2 inches is filled with liquid to a height of 9 inches. If the liquid is poured into a cylindrical travel mug with an inside diameter of 3 1/2 inches, what will be the height h of the liquid?

Volume of cylinder 1 = base area of cylinder 1 * height of cylinder 1

Volume of cylinder 2 = base area of cylinder 2 * height of cylinder 2

Since the volumes are equal - you can set the problem up as a ratio.