Question 1096053
Let {{{ d }}} = the one-way distance
Let {{{ s }}} = the speed to his house
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For the trip to his house:
(1) {{{ d = s*5 }}}
For return trip:
(2) {{{ d = ( s + 125 )*( 5 - 1.25 ) }}}
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(2) {{{ d = ( s + 125 )*3.75 }}}
(2) {{{ d = 3.75s + 468.75 }}}
and
(1) {{{ d = 5s }}}
Plug (1) into (2)
(2) {{{ 5s = 3.75s + 468.75 }}}
(2) {{{ 1.25s = 468.75 }}}
(2) {{{ s = 375 }}}
and
{{{ s + 125 = 375 + 125 }}}
{{{ s + 125 = 500 }}}
The speed on the return trip was 500 mi/hr
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check:
(1) {{{ d = 5*375 }}}
(1) {{{ d = 1875 }}} mi
and
(2) {{{ d = ( s + 125 )*( 5 - 1.25 ) }}}
(2) {{{ d = 500*3.75 }}}
(2) {{{ d = 1875 }}} mi
OK