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# Word Problems/Math

Question
when the mechanic at a at the car dealership checked the cars on the lot, he found that some were 1/2 full of gas and some were 1/4 full.  There were a total of 85 cars but only enough gas to fill 30 tanks. All of the cars have the same size gas tank.  How many cars were 1/2 full?

Let x=# of cars that are 1/2 full of gas, then 85-x=# of cars that are 1/4 full

Thus, (1/2)x + (1/4)(85-x) = 30 ... solving for x:
(1/2)x + 85/4 - (1/4)x = 30
(1/4)x = 30-85/4, now multiply by 4
x = 4(30-85/4)
= 120-85 = 35

35 cars were 1/2 full.

Abe

Word Problems

Volunteer

#### Abe Mantell

##### Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

##### Experience

Over 15 years teaching at the college level.

Organizations
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook