Question 571510
Let {{{ s }}} = her speed walking in km/hr
{{{ 3s }}} = her speed running in km/hr
Let {{{ d }}} = distance traveled walking in km
{{{ 36 - d }}} = distance traveled running in km
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Her equation walking:
(1) {{{ d = s*3 }}}
Her equation running:
(2) {{{ 36 - d = 3s*2 }}}
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(2) {{{ 36 - d = 6s }}}
Substitute (1) into (2)
(2) {{{36 - 3s = 6s }}}
(2) {{{ 9s = 36 }}}
(2) {{{ s = 4 }}}
Her speed walking was 4 km/hr
check answer:
(1) {{{ d = s*3 }}}
(1) {{{ d = 4*3 }}}
(1) {{{ d = 12 }}}
and
(2) {{{ 36 - d = 3*4*2 }}}
(2) {{{ 36 - d = 24 }}}
(2) {{{ d = 12 }}}
OK