how do i solve this problem

Question

A boat traveled down the Mississippi River with a steady current of 4 km/h to a casino in 2 hours and 20 minutes. It

returned home against the same current, but the trip took one hour and 40 minutes longer. Find r, the speed of the boat

in still water, and d, the distance between home and the casino.

Answer 1

2 hours and 20 minutes = 2 and 1/3 hour = 7/3 hours

1 hour and 40 minutes = 1 and 2/3 hour = 5/3 hours

Adding them together is 4 hours

D = r t

R is the speed of the boat

D = (R+4)*7/3 <--- downstream with the current

D = (R-4)* 4

(7/3)(R+4) = 4(R-4)

7(R+4) = 12(R-4)

7R + 28 = 12R - 48

28+48 = 12R - 7R

76 = 5R

R = 76/5 = 15.2

(15.2+4)* 7/3 = 44.8

(15.2 - 4)*4 = 11.2*4 = 44.8

The speed of the boat is 15.2

The distance is 44.8