One PS question from GMATPrep

wakaH

It is from the download software...

A certain car average 25 miles per gasoline when driven in the city and 40 miles per gasoline on the highway. According to these rates, which of the following is the closest to the number of miles per gallon that car average when it is driven 10 miles in the city and then 50 miles on the highway?

A. 28

B. 30

C. 33

D. 36

E. 38

The correct answer is---> D

Would someone kindly help me out on this? Quite confused...THANKS!!

(Sorry to type in English...because here I can only type in English...welcome to discuss in Chinese^^)

shirley8707

就是求平均每加仑的英里数:

用总路程:10+50=60MILES

还有一共的加仑: 10/25+50/40=

两者相除

帮我倒杯水

 in the city: 1 gallon 25 miles, so 0.4 gallon 10 miles

on the highway: 1 gallon 40 miles, so 1.25 gallon 50 miles

开了 10 + 50 miles, 用了 0.4+1.25 gallon

miles per gallon that car average..: 相除得36

wakaH

Really thanks to both of your prompt help!!

I think I simply made a mistake on calculation...