Question 471094
Let {{{ d }}} = number of days the person can rent the car
The formula to use is:
(cost of the rental) = (cost per day)x(number of days) + (cost per mile)x(number of miles)
and
(number of miles) = (miles per day)x(number of days)
given:
Cost per day = {{{25}}} dollars/day
Cost per mile = {{{ .02 }}} dollars/mi
Miles per day = {{{ 90 }}} mi/day
The formula must be OK dimensionally, that is
it must be dollars = dollars
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{{{ 200 = 25*d + .02*90*d }}}
{{{ 200 = 25d + 1.8d }}}
{{{ 200 = d*(25 + 1.8) }}}
{{{ 26.8d = 200 }}}
{{{ d = 7.463 }}}
The fraction of a day would not be allowed, so
the person could rent the car for 7 days
That means 
{{{ 25*7 + .02*90*7 }}}
{{{ 175 + 12.6 }}}
{{{ 187.6 }}}
They would spend $187.60