Answer :
120 parts / 2 hours = 60 parts per hour
60 parts per hour * 9 hours = 540 parts
60 parts per hour * 9 hours = 540 parts
first we find one hour rate means 120 / 2 =60 means 60 parts in one hour so now we will find 9 hours rate just multiply 60 by 9 = 540
