Question 1084998

You and a friend decide to row down river, have a picnic and then row back home. The picnic spot is 20 miles from home. It takes you 2 hours to row with the current to the picnic spot and 3 hours and 20 minutes to row back after the picnic. Determine the rate of the current and the rate at which you rowed.
<pre>Let rowing speed be S, and current speed, C
Then rowing with the current gives: {{{matrix(1,6, S + C = 20/2, "=====>", S + C = 10, "--------", eq, "(i)")}}}
Rowing against the current gives: {{{matrix(1,12, S - C = 20/(3 + 20/60), "=====>", S - C = 20/(3&1/3), "====>", S - C = 20/(10/3), "=====>", S - C = 20 * 3/10, "=====>", S - C = 6, "-------", eq, "(ii)")}}}
2S = 16 ------ Adding eqs (ii) & (i) 
S, or rowing-speed = {{{highlight_green(matrix(1,4, 16/2, or, 8, mph))}}}
Now, you find the speed of the current!