Question 686131
I think of one car as standing still and the other car
moving away from it at the sum of their speeds
Let {{{ s }}} = the speed of the faster car in km/hr
{{{ s - 10 }}} = the speed of the slower car in km/hr
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{{{ 600 = ( s + s - 10 )*4 }}}
{{{ 600 = ( 2s - 10 )*4 }}}
{{{ 600 = 8s - 40 }}}
{{{ 8s = 640 }}}
{{{ s = 80 }}}
{{{ s - 10 = 70 }}}
The speeds of the cars were 80 km/hr and 70 km/hr
check:
{{{ d[1] = 80*4 }}}
{{{ d[1] = 320 }}}
and
{{{ d[2] = 70*4 }}}
{{{ d[2] = 280 }}}
and
{{{ d[1] + d[2] = 320 + 280 }}}
{{{ d[1] + d[2] = 600 }}}
OK