Question 121396
100X+20(X-3)=1200
100X+20X-60=1200
120X=1200+60
120X=1260
X=1260/120
X=10.5 HOURS WAS BILLED FOR THE ENGINEER OR:
100*10.5=$1050 WAS THE ENGINEER'S BILL.
20(10.5-3)=20*7.5=$150 WAS THE ASSISTANT'S BILL.
PROOF
100*10.5+20*7.5=1200
1050+150=1200
1200=1200