Question 1059753
Let s be the speed of the boat, and c be the speed of the current. Then:
87/(s+c)=3
3s+3c=87, and
76/(s-c)=4
4s-4c=76. So:
12s+12c=348
12s-12c=228
24s=576
s=24
c=5
The boat goes 24 kph; the current is 5 kph. ☺☺☺☺