Question 1104699
Let {{{ c }}} = the rate of the current in mi/hr
Let {{{ s }}} = the speed of the boat in still water
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Traveling with the current:
(1) {{{ 36 = ( s + c )*2 }}}
Traveling against the current:
(2) {{{ 42 = ( s - c )*3 }}}
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(1) {{{ 2s + 2c = 36 }}}
(1) {{{ s + c = 18 }}}
and
(2) {{{ 3s - 3c = 42 }}}
(2) {{{ s - c = 14 }}}
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Add (1) and (2)
{{{ 2s = 32 }}}
{{{ s = 16 }}}
The speed of the boat in still water is 16 mi/hr
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check:
(1) {{{ s + c = 18 }}}
(1) {{{ 16 + c = 18 }}}
(1) {{{ c = 2 }}}
and
(2) {{{ s - c = 14 }}}
(2) {{{ 16 - c = 14 }}}
(2) {{{ c = 2 }}}
OK