Question 921102
The 1st car's head start is:
{{{ d[1] = 30*2 }}}
{{{ d[1] = 60 }}}
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Start a stopwatch when the 2nd car leaves
Let {{{ t }}} = the time on the stopwatch
when the cars have traveled the same distance
Let {{{ d }}} = the distance the 2nd car travels
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1st car's equation:
(1) {{{ d - 60 = 30t }}}
2nd car's equation:
(2) {{{ d = 40t }}}
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By substitution:
(1) {{{ 40t - 60 = 30t }}}
(1) {{{ 10t = 60 }}}
(1) {{{ t = 6 }}}
In {{{ 2 + 6 = 8 }}} hrs after the 1st car leaves
both cars have traveled the same distance
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check:
(2) {{{ d = 40*6 }}}
(2) {{{ d =240 }}} mi
and
(1) {{{ d - 60 = 30*6 }}}
(1) {{{ d = 180 + 60 }}}
(1) {{{ d = 240 }}}
OK
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Note that the 1st car travels {{{ 240 - 60 = 180 }}} mi
during the time the 2nd car travels {{{ 240 }}} mi, 
but the total miles for each car is the same: {{{ 240 }}} mi