human
Jack wants to send thank you cards to everyone who got him a gift for his wedding. He sent out 200 invitations. 90% of people RSVPed but only 80% of people who RSVPed actually showed up. Then 10 people who showed up didn't get a gift. How many thank you cards does he need?
assistant
How many people RSVPed? ** He got 200*.9=<<200*.9=180>>180 RSVP
How many people showed up? ** Of those only 180*.8=<<180*.8=144>>144 people showed up
How many people need thank you cards? ** So only 144-10=<<144-10=134>>134 got him gifts and hence need thank you cards.
#### 134