Question 763497
Let {{{ s }}} = the speed of the slower car in km/hr
{{{ 2s }}} = the speed of the faster car in km/hr
Let {{{ d }}} = the distance in km the slower car travels in 5 hrs
{{{ d + 275 }}} = the distance in km the faster car travels in 5 hrs
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Slower car:
(1) {{{ d = s*5 }}}
Faster car:
(2) {{{ d + 275 = 2s*5 }}}
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(2) {{{ d + 275 = 10s }}}
Substitute (1) into (2)
(2) {{{ 5s + 275 = 10s }}}
(2) {{{ 5s = 275 }}}
(2) {{{ s = 55 }}} 
{{{ 2s = 110 }}}
The slower car travels at 55 km/hr
The faster car travels at 110 km/hr
check:
(1) {{{ d = s*5 }}}
(1) {{{ d = 5*55 }}}
(1) {{{ d = 275 }}}
and
(2) {{{ d + 275 = 2s*5 }}}
(2) {{{ d + 275 = 2*55*5 }}}
(2) {{{ d = 550 - 275 }}}
(2) {{{ d = 275 }}}
OK