Question 769209
Speed of boat = x
86/x + 5 = 43/x - 5
Cross multiply
86(x - 5) = 43(x + 5)
86x - 430 = 43x + 215
86x - 43x = 215 + 430
43x = 645
x = 15
Speed of boat = 15mph
Hope this helps.
:-)