Answer:
8 mph
Step-by-step explanation:
Let's say x is the speed of the current, and t is the time. When travelling with the current, the boat's speed is 54 + x. When travelling against the current, the boat's speed is 54 – x.
Distance = rate × time
124 = (54 + x) t
92 = (54 – x) t
Solve for t in each equation:
t = 124 / (54 + x)
t = 92 / (54 – x)
Set equal:
124 / (54 + x) = 92 / (54 – x)
Cross multiply:
124 (54 – x) = 92 (54 + x)
Distribute and solve:
6696 – 124x = 4968 + 92x
1728 = 216x
x = 8
The speed of the current is 8 mph.
