Question 1013510
Let {{{ t }}} = time in hours spent biking
{{{ 3 - t }}} = time in hours spent walking
Let {{{ s }}} = his walking speed in mi/hr
{{{ 2s }}} = his speed biking
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His equation for biking:
(1) {{{ 14 = 2s*t }}}
His equation for walking:
(2) {{{ 5 = s*( 3-t ) }}}
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(1) {{{ s = 14/(2t) }}}
(1) {{{ s = 7/t }}}
and
(2) {{{ 5 = s*( 3-t ) }}}
(2) {{{ 5 =(7/t)*( 3-t ) }}}
(2) {{{ 5 = 21/t - 7 }}}
(2) {{{ 21/t = 12 }}}
(2) {{{ 12t = 21 }}}
(2) {{{ t = 1.75 }}}
and
(1) {{{ s = 7/t }}}
(1) {{{ s = 7/1.75 }}}
(1) {{{ s = 4 }}}
He walked 4 mi/hr
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check:
(2) {{{ 5 = s*( 3-t ) }}}
(2) {{{ 5 =4*( 3-1.75 ) }}}
(2) {{{ 5 = 4*1.25 }}}
(2) {{{ 5 = 5 }}}
and
(1) {{{ 14 = 2s*t }}}
(1) {{{ 14 = 2*4*1.75 }}}
(1) {{{ 14 = 8*1.75 }}}
(1) {{{ 14 = 14 }}}
OK