a company makes 100 bags

35 of the bags have buttons no zips
34 of the bag have zips no buttons
27 of the bags have neither zips or buttons
a bag is selected at random
what is the probablity the bag has buttons?

2 answers

If there are x bags with both buttons and zips, then
34+35+x = 100-27
P(buttons) = (35+x)/100
35 + 34 + 27 = 96

What happened to the other 4?

35/100 = 7/20