Solution:

28 is the required number.

28 * 3 - 2 = 82.

Solution:

25

Distance between Tribe Q and Tribe S = 40km
=> Distance between Tribe Q and Tribe R + Distance between Tribe R and Tribe S = 40km
=> Distance between Tribe Q and Tribe R + (Distance between Tribe Q and Tribe R - 10) = 40 km
=> 2 * Distance between Tribe Q and Tribe R = 50km
=> Distance between Tribe Q and Tribe R = 25km

Solution:

84

Explanation:
Let us assume that Adam lived for p years.

p/6 + p/12 + p/7 + 5 + p/2 + 4 = x
=> p = 84.

Therefore, Adam lived for 84 years.

Solution:

T = 1
W = 3
O = 8
H = 9
R = 0
E = 4

For the full multiplication, see the figure.

Solution:

The man is 84 years old.
The son is 49 years old.
The grandson is 7 years old.

Solution:

9

Explanation:
5 cartons for large boxes = 5 * 6 = 30 boxes
4 cartons for small boxes = 4 * 9 = 36 boxes

He will need 9 cartons to place 66 boxes.

Solution:

First shop: 80 pencils
80 * 5 paise = 400 paise = 4 rupees

Second Shop: 1 Pencil
1 * 1 = 1 Rupee

Third Shop: 19 pencils
19 * 5 rupees = 95 rupees

4 + 1 + 95 = 100 rupees.

Solution:

102

Explanation:
The total number of animals in the zoo is one hundred and two i.e. thirty-four animals of each kind.

Since we already know that the number of each animal is same, each single deer, spider and cricket will have a total of eighteen legs.

Now, 612/18 = 34.

Therefore, total number of animals:
34 * 3 = 102

Solution:

Let us denote the chocolates with p, q and r.
We can frame the following two equations now
p + q + r = 100 ------ (1)
5p + 3q + 0.5r = 100
or 10p + 6q + r = 200 ---- (2)

Now, 2*[(Eq. 2) - (Eq.1)]
9p + 5q = 100
from this equation'p' should be a multiple of 5
for p = 5 ; q = 11
for p = 10 ; q = 2
for p = 15 or more q becomes -ve

Therefore, the two possible answers are
p = 5, q = 11, r = 84
p = 10, q = 2, r = 88

Solution:

Alex was one third of his father's age when he was 14. This goes back 31 years when his father was 42 years old.