John needs $20 to buy a ticket to a

show.He earned 1/4 of the money on
Monday, 2/5 onTuesday,and 1/10 on
Wednesday. What fraction of the money does John still need to earn?

1 - 1/4 - 2/5 - 1/10 = 1 - 5/20 - 8/20 - 2/20 = ?