PP-T1-DS46

[slin0717]

46. 3960-!-item-!-187;#058&003582

How many hours did it take Helen to drive from her house to her parents' house?
(1) Helen's average speed on this trip was 72 kilometers per hour.

(2) If Helen's average speed on this trip had been 8 kilometers per hour greater, it would have taken her 1 hour less.

答案:C

能請版上的朋友幫忙解答一下嗎,謝謝

[amyliang]

D/S=T
(1) D/72=T
(2) D/(72+8)=T-1

(1)+(2) I believe that you can solve this equation