Question 1046371
Let {{{ s }}} = the average speed on the outbound trip in mi/hr
{{{ s + 21 }}} = the average speed on the return trip in mi/hr
Let {{{ d }}} = the one way distance to Las Vegas in miles
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Equation for outbound trip:
(1) {{{ d = s*17 }}}
Equation for return trip:
(2) {{{ d = ( s + 21 )*10 }}}
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Substitute (1) into (2)
(2) {{{ 17s = ( s + 21 )*10 }}}
(2) {{{ 17s = 10s + 210 }}}
(2) {{{ 7s = 210 }}}
(2) {{{ s = 30 }}}
The speed on the outbound trip is 30 mi/hr
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check:
(1) {{{ d = s*17 }}}
(1) {{{ d = 30*17 }}}
(1) {{{ d = 510 }}} mi
and
(2) {{{ d = ( s + 21 )*10 }}}
(2) {{{ d = ( 30 + 21 )*10 }}}
(2) {{{ d = 51*10 }}}
(2) {{{ d = 510 }}} mi