Question

how would you approach this question ?

Answer 1

and how would one find the number of people that use all three sets ?

Answer 2

wait after having my lunch i will solve

Answer 3

let A intersection B intersection C =x
A intersection B=25
hence A intersection B not in C=25-x
A intersection C=20
A intersection C not in B=20-x
B intersection c=30
B intersection C not in A=30-x
only A=65-(20-x+x+25-x)=20+x ....(1)
Only B=75-(25-x+x+30-x)=20+x
Only C=55-(20-x+x+30-x)=5+x
Now (20+x)+(20-x)+(25-x)+x+(20+x)+(30-x)+(5+x)+15=150
135+x=150
x=150-135=15
your question is upto no (1) only
though i have solved ,number of people who used all three sets.

Answer 4

thank you for your help

Answer 5

yw