Question 738657
Let {{{ s }}} = speed for motorbike in mi/hr
{{{ s - 20 }}} = speed for bikein mi/hrLet {{{ t }}} = the time for both in hrs
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Equation for motorbike:
(1) {{{ 40 = s*t }}}
Equation for bike:
(2) {{{ 15 = ( s-20 )*t }}}
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(2) {{{ 15 = s*t - 20t }}}
Substitute (1) into (2)
(2) {{{ 15 = 40 - 20t }}}
(2) {{{ 20t = 25 }}}
(2) {{{ t = 5/4 }}}
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(1) {{{ s = 40/t }}}
(1) {{{ s = 40/( 5/4 ) }}}
(1) {{{ s = 160/5 }}}
(1) {{{ s = 32 }}}
{{{ s - 20 = 12 }}}
The motorbike travels at 32 mi/hr
The bike travels at 12 mi/hr
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check:
(2) {{{ 15 = s*t - 20t }}}
(2) {{{ 15 = 32*(5/4) - 20*(5/4) }}}
(2) {{{ 15 = 40 - 25 }}}
(2) {{{ 15 = 15 }}}
OK