word problem

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word problem

Ryan is working his way through school.  He works two part-time jobs for a total of 26 hours a week.  Job A pays $6.20$ per hour, and Job B pays $6.90 per hour.  How many hours did he work at each job the week that he made $168.90
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Re: word problem

a = number of hours at $6.20 per hour job
b = number of hours at $6.90 per hour job

a + b = 26   {TIME}
6.2a + 6.9b = 168.9   {PAY}

-6.2a - 6.2b = -161.2   {multiplied 1st equation by -6.2 to eliminate the a when adding}
 6.2a + 6.9b = 168.9   {second equation stays the same}
-------------------------
0.7b = 7.7   {added the two equations}
b = 11   {divided}

a + b = 26   {first equation}
a + 11 = 26   {substituted 11, in for b, into first equation}
a = 15   {subtracted 11 from each side}

15 hours at the $6.20 per hour job
11 hours at the $6.90 per hour job


@AlgebraHouse