There are only 7 regions. Name them and label them.
A - A alone
B - B alone
C - C alone
AB - A&B but not C
AC - A&C but not B
BC - B&C but not A
ABC - All Three
AB+AC+BC+ABC = 35at least two are read by 35% of the population
C + AC + BC + ABC = 45newspaper C is read by 45% of the population.
ABC = 10all the three papers are read by 10%
This is where I get lost. I do not know what this means.A and B are read by 15%
It might be: AB = 15
If so, a little substitution and subtraction solve the problem.
AB = 15
ABC = 10
AC+BC = 10
C = 25