Answer:
4 mph
Step-by-step explanation:
Travel time is proportional to distance and inversely proportional to speed. If c represents the speed of the current in miles per hour, an equation for the total trip time is ...
825/(29 -c) +825/(29 +c) = 58 . . . . . . hours travel time
825(29 +c) +825(29 -c) = 58(29 -c)(29 +c)
58c² -928 = 0 . . . . . . . rearrange to standard form
58(c -4)(c +4) = 0 . . . . factor
Values of c that satisfy this equation are 4 and -4. For the purpose here, we'll choose the positive solution.
The speed of the current is 4 miles per hour.
