the answer is b, just divide 50 by 59 and multiply that sum to 6.4
Answer:
How many people are not allergic to any of the three choices? 22
How many people are allergic to all three choices? 1
How many people are allergic to both dogs and cats but not allergic to pollen? 7
How many people are allergic to cats only? 18
You can read it of the graph which is (1,3) or also calculate it with vectors:
calculate the vector CD:
(5-(-3),2-4)=(8,-2)
to calculate the midpoint you need half of the vector length:
(8,-2)/2=(4,-1)
add the vector to C:
(-3,4)+(4,-1)=(1,3)=midpoint of CD
so it's the third option
