Question 279709
An electrician, a carpenter, and a plumber are hired to work on a house. The electrician earns $21 per hour, the carpenter $19.50 per hour, and the plumber $24 per hour. The first day on the job, they worked a total of 21.5 hours and earned a total of $469.50. If the plumber worked 3 more hours than the carpenter did, how many hours did each work? Write the system 
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Hours Equation:::: e + c + p = 21.5 hrs 
Equation:::::::::21e+19.5c + 24p = 469.5
Relative Hrs::    0e -  c      p = 3
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I used a matrix method and got the following:
e = 6.5 (electrician hrs.)
c = 6 (carpenter hrs.)
p = 9 (plumber hrs.)
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Cheers,
stan H.