The boat could travel 112 miles downstream in 4 hours but re

The boat could travel 112 miles downstream in 4 hours but required 6 hours to travel 48 miles upstream. What was the speed of the boat in still water and what was the speed of the current?

Solution

x+y=112/4 & x-y=48/6
x+y=28 & x-y=8
x=28-y
(28-y)-y=8
28-2y=8
-2y=-20
y=-20/-2
y=10 this is the speed of the current
x+10=28
x=28-10
x=18 the speed of the boat in still water.
proof
18-10=48/6
8=8