Please help. Any help will be greatly appreciated

Question

A boat travels 52 mi upstream against the current in the same amount of time it takes to travel 78 mi downstream with the current. If the current is 5mph, what is the speed of the boat in still water?

Answer 1

rate (r) * time (t) = d (distance)

solving for time:

t = d/r

for upstream

d = 52

r = r - 5

t = 52/(r-5)

for downstream

d = 78

r = r + 5

t = 78/(r+5)

since times are equal:

52/(r-5) = 78/(r+50)

cross-multiply to get:

78 * (r-5) = 52 * (r+5)

78r - 390 = 52r + 260

26r = 650

r = 25