Posted by Paula on .
A riverboat cruise line has a boat that can travel 76 mi downstream in the same time that it takes to travel 52 mi upstream. The speed of the current in the river is 1.5 mph. Find the speed of the boat in still water.

Algebra 
Reiny,
speed of boat in still water  x mph
speed against current = x1.5
speed downstream = x+1.5
time to go 75 miles downstream = 75/(x+1.5)
time to go 52 miles upstream = 52/(x1.5)
so 75/(x+1.5) = 52/(x1.5)
crossmultiply and solve for x 
Algebra 
Paula,
so answer is 8?
76x  114 = 52x + 78
24x = 192
x = 8