Question

I know I posted this already but there is a typo.

There are 49 mice in a pet shop.
30 mice are white.
27 mice are male.
18 mice have short tails.
8 mice are white and have short tails.
11 mice are male and have short tails.
7 mice are male but neither white nor short-tailed.
5 mice have all three characteristics and
2 have none.

Note:
W represents white mice
M represents male mice
S represents short-failed mice



I made a venn diagram but need help on...
n(M' U S)
The answer says 22+18-7=33
I know that M' means 49-27=22 and the union sign means add the 18 short tails but where does 7 come from? I know you have to subtract the overlap but according to my Venn diagram, the overlap between M and D is 5+6=11.