Question 879274
What is the train's head start?
{{{ d[1] = 85*2.25 }}}
{{{ d[1] = 191.25 }}} mi
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Let {{{ d }}} = the distance the plane travels 
when they are {{{ 750 }}} mi apart
Let {{{ t }}} = the time that the plane travels
when they are {{{ 750 }}} mi apart
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Plane's equation:
(1) {{{ d = 225t }}}
Train's equation:
(2) {{{ ( d - 191.25 ) - 750 = 85t }}}
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(2) {{{ d - 941.25 = 85t }}}
Substitute (1) into (2)
(2) {{{ 225t - 941.25 = 85t }}}
(2) {{{ 140t = 941.25 }}}
(2) {{{ t = 6.7232 }}}
also {{{ .7232*60 = 43 }}}
It will take them 6 hrs and 43 min
check:
(1) {{{ d = 225t }}}
(1) {{{ d = 225*6.7232 }}}
(1) {{{ d = 1512.72 }}}
and
(2) {{{ ( d - 191.25 ) - 750 = 85t }}}
(2) {{{ ( d - 191.25 ) - 750 = 85*6.7232 }}}
(2) {{{ d - 941.25 = 571.472 }}}
(2) {{{ d = 1512.72 }}}
OK