Answer:
97
There are 97 people who ate pizza (of these three activities) last Friday night.
Explanation:
We have
A= 159 watched TV
B=157 hung out with friends
C=30 watched TV and ate pizza, but did not hang out with friends
D=30 watched TV and hung out with friends, but did not eat pizza
E= 48 hung out with friends and ate pizza, but did not watch TV
F=27 watched TV, hung out with friends, and ate pizza
G= 69 did not do any of these three activities
We find out the number of people eating pizza by deducting the number of people not eating pizza from the total number.
So people not eating pizza are listed as A, B, D, G
Total = 512
Those who only ate pizza= total - (A+B+D+G)
= 512 - (159+157+30+69)
= 512- 415= 97
There are 97 people who ate pizza (of these three activities) last Friday night.