Question 1093232
First find John's head start in terms of miles
Let {{{ s }}} = John's speed in mi/hr
{{{ d[1] = s*1 }}}
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Start a stop watch when Wilbur leaves.
It will stop in 1 hr
Let {{{ d }}} = the distance in miles Wilbur travels
in the 1 hr on the stop watch
Wilbur's equation:
(1) {{{ d = ( s - 12 )*1 }}}
John's equation:
(2) {{{ ( 159 - d ) - d[1] = s*1 }}}
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(2) {{{ 159 - d - s*1 = s*1 }}}
(2) {{{ 159 - d = 2s }}}
(2) {{{ d = 159 - 2s }}}
and
(1) {{{ d = s - 12 }}}
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Set (1) = (2)
{{{ 159 - 2s = s - 12 }}}
{{{ 3s = 171 }}}
{{{ s = 57 }}}
John's speed is 57 mi/hr
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check answer:
(1) {{{ d = s - 12 }}}
(1) {{{ d = 57 - 12 }}}
(1) {{{ d = 45 }}} mi
and
(2) {{{ 159 - d - s = s }}}
(2) {{{ 159 - d = 2*57 }}}
(2) {{{ d = 159 - 114 }}}
(2) {{{ d = 45 }}} mi
OK