Question 48227
Let x be the boat's speed and let y be the speed of the current
EQUATION 1:
upstream = -
-->3x-3y=45
EQUATION 2:
Downstream = +
-->2x+2y=50
Multiply E1 by 2 and E2 by 3
6x-6y=90
6x+6y=150
add:
12x=240
x=20

3(20)-3y=45
-3y=-15
y=5
Hence, the speed of the boat is 20mph and the speed of the current is 5mph.
Paul.