Question 323096
Let {{{d}}} = the distance he drove in AM
Let {{{r}}} = his speed in the AM
{{{8 - 5 = 3}}} hrs driving time in PM
given:
{{{d = r*5}}}
{{{310 - d = (r + 10)*3}}}
By substitution:
{{{310 - 5r = 3r + 30}}}
{{{8r = 310 - 30}}}
{{{8r = 280}}}
{{{r = 35}}}
He drove 35 mi/hr in the AM
check:
{{{d = 5*35}}}
{{{d = 175}}}
{{{310 - d = (r + 10)*3}}}
{{{310 - 175 = (35 + 10)*3}}}
{{{135 = 45*3}}}
{{{135 = 135}}}
OK