Question 673883
Let {{{ s }}} = the speed of the local train
Let {{{ t }}} = the travel time for the local train
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Equation for local train:
(1) {{{ 220 = s*t }}}
Equation for express train:
(2) {{{ 220 = 2s*( t - 2 ) }}}
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(2) {{{ 220 = 2*s*t - 4s }}}
Substitute (1) into (2)
(2) {{{ 220 = 2*220 - 4s }}}
(2) {{{ 4s = 440 - 220 }}}
(2) {{{ 4s = 220 }}}
(2) {{{ s = 55 }}}
{{{ 2s = 110 }}}
The express train's speed is 110 m,i/hr
The local train's speed is 55 mi/hr
check answer:
(1) {{{ 220 = s*t }}}
(1) {{{ t = 220/55 }}}
(1) {{{ t = 4 }}}
and
(2) {{{ 220 = 2s*( 4 - 2 ) }}}
(2) {{{ 220 = 4s }}}
(2) {{{ s = 55 }}}
OK