Question 796173
Going upstream:
(1) {{{ 24 = ( x - y )*3 }}}
Going downstream:
(2) {{{ 36 = ( x + y )*3 }}}
----------------------------
(1) {{{ 3x - 3y = 24 }}}
(1) {{{ x - y = 8 }}}
and
(2) {{{ 3x + 3y = 36 }}}
(2) {{{ x + y = 12 }}}
add the equations
{{{ 2x = 20 }}}
{{{ x = 10 }}}
and
(2) {{{ x + y = 12 }}}
(2) {{{ y = 2 }}}
The current is 2 mi/hr
The rate in still water is 10 mi/hr