Question 743648
Let {{{ d }}} = distance in miles that Mary travels
{{{ d + 35 }}} = distance in miles that John travels
Let {{{ t }}} = time in hours that John's trip takes
{{{ t + 1/4 }}} = time in hours that Mary's trip takes

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John's equation:
(1) {{{ d + 35 = 60t }}}
Mary's equation:
(2) {{{ d = 40*( t + 1/4 ) }}}
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(2) {{{ d = 40t + 10 }}}
Substitute (2) into (1)
(1) {{{ 40t + 10 + 35 = 60t }}}
(1) {{{ 20t = 45 }}}
(1) {{{ t = 2.25 }}}
and
{{{ t + 1/4 = 2.5 }}}
John drives for 2 hrs 15 min
Mary drives for 2 hrs 30 min
check:
(1) {{{ d + 35 = 60*2.25 }}}
(1) {{{ d = 135 - 35 }}}
(1) {{{ d = 100 }}}
and
(2) {{{ d = 40*( 2.25 + 1/4 ) }}}
(2) {{{ d = 40*2.5 }}}
(2) {{{ d = 100 }}}
OK