Answer:
Step-by-step explanation:
This is a proportional question. If you learn how to keep things together, they are not only easy to do, they are mechanical: they are all done exactly the same way.
tanks of gas different tanks of gas
========== = ================
hours different hours.
initial tank of gas = 3/4 tank
initial hours = 9/2 = 4.5 hours
final tanks of gas = X
final time = 12 hours.
Solution
3/4 x
==== = ==============
4.5 12
Cross multiply
4.5x = 12*3/4 Combine the right
4.5x = 36/4 Simplify
4.5x = 9 Divide both sides by 4.5
x = 9/4.5
x = 2
So she will need 2 tankfuls.
