Answer:
The current is 5 mph
Step-by-step explanation:
The current helps the boat going down stream and hinders going up so it adds to the speed downstream and subtracts going up.
speed downstream is 20miles/40minutes =1 mi per 2 min. Or 30 mph
Speed upstream is
20 miles/ 60 minutes = 1 mile per 3minutes or 20 mph
So if the speed of the boat is the same (s) then downstream the boat travels
S+c =30 mph and s-c =20mph upstream if c is tge current speed
So s=30-c and s=20+c
So. 30-C=20+c
10=2C
5=C
The current is 5 mph
