# SOLUTION: Please help me with this!! A carpenter charges a set fee for each job in addition to his hourly charge. If a carpenter bills a customer \$150 for a job that takes him 3 hours an

Algebra ->  Algebra  -> Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Please help me with this!! A carpenter charges a set fee for each job in addition to his hourly charge. If a carpenter bills a customer \$150 for a job that takes him 3 hours an      Log On

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 Question 157925: Please help me with this!! A carpenter charges a set fee for each job in addition to his hourly charge. If a carpenter bills a customer \$150 for a job that takes him 3 hours and bills a second customer \$180 for a 6 hour job, how much would he charge for a job that takes him 9 hours? TIA! JoanneAnswer by nerdybill(6958)   (Show Source): You can put this solution on YOUR website!If a carpenter bills a customer \$150 for a job that takes him 3 hours and bills a second customer \$180 for a 6 hour job, how much would he charge for a job that takes him 9 hours? . Let x = set fee and y = hourly rate . Since we have two unknowns, we'll need to find two equations. . Equation 1: from: "a carpenter bills a customer \$150 for a job that takes him 3 hours" x + 3y = 150 . Equation 2: from: "and bills a second customer \$180 for a 6 hour job" x + 6y = 180 . Subtract equation 1 from equation 2: x + 6y = 180 -x - 3y = -150 ---------------- 3y = 30 y = \$10/hour (rate) . To find x, substitute the above into equation 1 and solve for y: x + 3y = 150 x + 3(10) = 150 x + 30 = 150 x = \$120 (set fee) . Our equation for cost is: f(x) = 10x + 120 where x is the number of hours on the job To calculate for a 9-hour job: f(x) = 10x + 120 f(9) = 10(9) + 120 f(9) = 90 + 120 f(9) = \$210