<PRE><B>Question 197519</B>
Suv gets 17 miles per gallon (mpg) in city driving and 23 mpg in highway driving. 
The suv is driven 290 miles on 15 gallons of gas.
 How many miles were driven in the city and how many miles were driven on the highway
:
Let c = no. of miles driven in the city
Let h = no. of miles drive on the highway
:
c + h = 290
h = (290-c)
and
{{{c/17}}} + {{{h/23}}} = 15
multiply equation by 17*23 = 391, results:
23c + 17h = 391(15)
:
23c + 17h = 5865
:
substitute (290-c) for h:
23c + 17(290-c) = 5865
:
23c + 4930 - 17c = 5865
:
23c - 17c = 5865 - 4930
:
6c = 935
c = {{{935/6}}}
c = 155.8 mi in city
and
h = 290 - 155.8
h = 134.2 mi on the highway
:
:
Check solution on calc; enter:
{{{155.8/17}}} + {{{134.2/23}}} = 14.999 ~ 15</PRE>