A clerk can file cards at the rate of 120 cards per hour. He has a total of 900 cards to file. How many cards remain to be filed after 6 hours?

Answer 1

rate is 120 cards per hour y=120x
y=120(6)
120(6)= 720
he files 720 cards after 6 hours
so 900-720= 180
180 cards left to file