10th grade algebra not ms.sue
posted by natalie .
a 68 mile trip uses 2 gallons of gas. how many gallons would you use on a 110 mile trip? round to the nearest tenth of a gallon.

I would just set it up as a proportion and cross multiply. 68/2=110/? or 2/68=?/110

what is the ? for

The ? is the answer. You solve for that.

how like what do i do

68 = 110
 
2 x
This is how to set up the proportion that zorro was talking about, although he did it incorrectly.
Cross multiply:
110 (2) = 220
68 (x) = 68x
Therefore:
220 = 68x
Solve for x by dividing by 68 on both sides.