Question

Two rafts are traveling In opposite directions on a straight river. The raft going with the current is traveling at a speed of 12 mph. The raft going against the current is traveling at a speed of 70 miles per hour. Both rafts travel the river for two hours. Which equation represents the situation? Assume the raft traveling with the current travels X miles in the raft traveling against the current travels y miles.
A. 12/x - 7/y = 1/2
B. 12x + 7y = 2
C. x/12 - y/7 = 2
D. x/12 + y/7 = 4
E. 12x + 7y = 4

Answer 1

Time =(distance)/speed
Time taken by the raft going with the current to travel x miles is:
12/x hours
Time taken by the raft going against the wind is:
7/y
Total time taken for both raft is 4 hours thus:
12/x+7/y=4
hence the answer is:
D. x/12 + y/7 = 4