SOLUTION: Two mechanics worked on a car. The first mechanic charged $45 per hour, and the second mechanic charged $85 per hour. The mechanics worked for a combined total of 20 hours, and tog

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Two mechanics worked on a car. The first mechanic charged $45 per hour, and the second mechanic charged $85 per hour. The mechanics worked for a combined total of 20 hours, and tog      Log On


   

Question 414122: Two mechanics worked on a car. The first mechanic charged $45 per hour, and the second mechanic charged $85 per hour. The mechanics worked for a combined total of 20 hours, and together they charged a total of $1100 . How long did each mechanic work?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a = hours that 1st mechanic worked
Let b = hours that 2nd mechanic worked
given:
(1) 45a+%2B+85b+=+1100
(2) a+%2B+b+=+20
Multiply both sides of (2) by 45 and
subtract (2) from (1)
(1) 45a+%2B+85b+=+1100
(2) -45a+-+45b+=+-900
40b+=+200
b+=+5
and
(2) a+%2B+5+=+20
(2) a+=+15
1st mechanic worked 15 hrs
2nd mechanic worked 5 hrs