SOLUTION: Paul earns $4 an hour working at the librabry and $8 an hour mowing lawns. This week he worked 25 hours and earned $164. How many hours did he work at the librabry.

Question 25494: Paul earns $4 an hour working at the librabry and $8 an hour mowing lawns. This week he worked 25 hours and earned $164. How many hours did he work at the librabry.
Answer by Paul(988) (Show Source): You can put this solution on YOUR website!
LEt the working hours in the libaray be x
Let the workign hours of mowing a lawn be y
Now total hours was 25.
So x+y=25
y=25-x (subsistution)
Total money was $164
SO 4x+8y=164
Subsitute for y
4x+8(25-x)=164
4x-8x+200=164
-4x=-36
x=9
y=25-9
y=16

Hence he worked for 9 hours at the libabary, and about 16 hours for mowing the lawn.
Paul.
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