Question 1024241
Let {{{ c }}} = the rate of the current
Let {{{ s }}} = the speed of the boat in still water
{{{ s + c }}} = the speed of the boat going downstream
{{{ s - c }}} = the speed of the boat going upstream
-----------------------------------------
Equation for going upstream:
(1) {{{ 60 = ( s - c )*2 }}}
Equation for going downstream:
(2) {{{ 60 = ( s + c )*1 }}}
--------------------------
(1) {{{ s - c = 30 }}}
and
(2) {{{ s + c = 60 }}}
Add the equations:
{{{ 2s = 90 }}}
{{{ s = 45 }}}
-------------
(2) {{{ 60 = ( s + c )*1 }}}
(2) {{{ 60 = ( 45 + c )*1 }}}
(2) {{{ 60 = 45 + c }}}
(2) {{{ c = 15 }}}
The rate of the current is 15 mi/hr
-----------------------------
check:
(1) {{{ 60 = ( s - c )*2 }}}
(1) {{{ 60 = ( 45 - 15 )*2 }}}
(1) {{{ 60 = 30*2 }}}
(1) {{{ 60 = 60 }}}
OK