Answer: Peter worked 9 hours at job a
Explanation:
Step 1
Let the number of hours worked in job a = x
and number of hours worked in job b = y such that the total hours worked would be expressed as
x=y= 24 ---eqn 1
also since $6 and $9 dollar are paid per hour for the job and the total amount made is $189, it should be expressed as
6x + 9y =$189--- equation 2
Step 2
Now we have gotten two expressions to solve for number of hours, we can now solve
x+y= 24 ---eqn 1
6x + 9y =$189--- eqn 2
Using elimination method, we multiply equation 1 by 6 and subtract from equation 2
6x + 9y =189
-6x+6y=144
3y=45
y= 45/3 =15
To find x
x+y = 24
x+15=24
x= 24-15
x= 9
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Therefore Peter worked 9 hours at job a and 15 hours at job b