Question 1122830
(1) {{{ d = r*( 20/60 ) }}}
(2) {{{ d = ( r - 24 )*( 36/60 ) }}}
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By substitution:
{{{ (1/3)*r = (3/5)*( r - 24 ) }}}
Multiply both sides by {{{ 15 }}}
{{{ 5r = 9*( r - 24 ) }}}
{{{ 5r = 9r - 216 }}}
{{{ 4r = 216 }}}
{{{ r = 54 }}}
And
{{{ r - 24 = 30 }}}
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Her speed in light traffic is 54 mi/hr
Her speed in heavy traffic is 30 mi/hr
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Check:
(1) {{{ d = 54*(1/3) }}}
(1) {{{ d = 18 }}} mi
And
(2) {{{ d = 30*(3/5) }}}
(2) {{{ d = 18 }}} mi
OK