Posted by dawn on Monday, March 21, 2011 at 11:02pm.
to save fuel on the 240 km trip to the cottage, the Nakamura family reduce their usual average speed by 20 km/h. this lengthens their journey by 1 hour. what is the slower average speed?
i was told this question is not complete to answer? is that true?

math...?  Reiny, Tuesday, March 22, 2011 at 7:55am
normal speed  x km/h
time at normal speed = 240/x hours
reduced speed  x20 km/h
time at reduced speed = 240/(x20)
solve:
240/(x20)  240/x =1
hint: multiply each term by x(x2)