Question 941248
Let {{{ d }}} = distance in miles to work
Let {{{ s }}} = his speed on his bike in mi/hr
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Equation for riding bike:
(1) {{{ d = s*(3/4) }}}
Equation for driving car:
(2) {{{ d = ( s+14 )*(1/6) }}}
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By substitution:
{{{ s*(3/4) = ( s+14 )*(1/6) }}}
Multiply both sides by {{{ 12 }}}
{{{ 3*s*3 = 2*( s+14 ) }}}
{{{ 9s = 2s + 28 }}}
{{{ 7s = 28 }}}
{{{ s = 4 }}} 
{{{ s + 14 = 18 }}}
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(1) {{{ d = 4*(3/4) }}}
(1) {{{ d = 3 }}} 
The distance to work is 3 mi
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check:
(2) {{{ d = 18*(1/6) }}}
(2) {{{ d = 3 }}} mi
OK