Question 770058
Let {{{ t }}} = time in hrs for trip
{{{ t - 4*(21/60) }}} = actual time spent driving
{{{ t - 21/15 }}}
{{{ t - 7/5 }}} hrs
{{{ 456 = 75*(t - 7/5) }}}
{{{ 456 = 75t - 7*15 }}}
{{{ 75t = 456 + 105 }}}
{{{ 75t = 561 }}}
{{{ t = 7.48 }}}
You need 7.5 hrs
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check:
{{{ 21/15 = 1.4 }}}
{{{ 456 = 75*( t - 1.4 ) }}}
{{{ 456 = 75t - 105 }}}
{{{ 75*7.48 = 456 + 105 }}}
{{{ 561 = 561 }}}
OK