Question 848267
Let {{{ t }}} = the time in hours to go downstream
{{{ t + 5 }}} = the time to go upstream
Let {{{ d }}} = the distance in miles from A to B
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Equation for going downstream:
(1) {{{ d = 20t }}}
Equation for going upstream:
(2) {{{ d = 15*( t + 5 ) }}}
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Substitute (1) into (2)
(2) {{{ 20t = 15t + 75 }}}
(2) {{{ 5t = 75 }}}
(2) {{{ t = 15 }}}
and
(1) {{{ d = 20t }}}
(1) {{{ d = 20*15 }}}
(1) {{{ d = 300 }}}
the distance between A an B is 300 mi
check:
(2) {{{ d = 20t }}}
(2) {{{ 300 = 20t }}}
(2) {{{ t = 15 }}}
OK