Maths

400 divided into 8 catagories

0)nil
1)only a, only b, only c
2)a&b, b&c, a&c
3)abc

from information given
abc = 70
ab = 100-70 =30
ac = 80 - 70 =10
bc = 90 - 70 =20
a =150-70-30-10=40
b =170-70-30-20=50
c =160-70-10-20=60
nil =400-70-30-10-20-40-50-60=120

ai 400-120=280
ii 30+10+20=60
iii 40+50+60=150
b 120/400=30%