You are a self-employed plumber. your charges are: $22.50 per hour for labor, $0.50 per mile for travel to and from home, and the cost of materials plus 5%. your last job was 35 miles from home. you took 4.5 hours to complete the job. the parts cost $350. your invoice to the customer was for $468.75.

Given:
22.50 per hour of labor
0.50 per mile for travel to and from home
cost of materials plus 5%

last job:
35 miles from home, 4.5 hours, parts cost 350. invoice = 468.75

35 miles x 2 = 70 miles 
70 miles x 0.50 = 35 

4.5 hours x 22.50 = 101.25

350 x 1.05 = 367.50

Total: 35 + 101.25 + 367.50 = 503.75  this should be the amount in the invoice.

503.75 - 468.75 = 35 shortage from invoice.