AJB77 wrote:

Can you please post explanations?

ABJ,

I drew venn diagrams and that's why i summarized the venn diagrams above.

(115 - 81) = 34 = Telephone users alone.

Since 115 counts the number of T U L and T U E twice, we subract 28 and 53 (81) from 115 to get the number Telephone users.

39 - 38 = 1= Letters users alone (same rationale as above)

64 - 63 = 1 = E-mail users alone (same as above)

140 - (34 + 1 + 1 + 28 + 53 + 10 +3)

140 - 130

= 10

Another alternative way is to fill out the venn diagrams from inside out.

start from the middle and put 3

Intersection of T and L is 28 -3 = 25

Intersection of T and E is 53-3 = 50

Intersection of L and E is 10 -3 = 7

T alone 115 - (25 + 3+ 50) = 37

L alone 39 - (25 + 3 + 7) = 4

E alone 64 - (50 + 3 + 7) = 4.

140 - (3 + 25 + 50 + 7 + 37 + 4 + 4) should be the number of people using neither L, T or E.

140 -130

= 10