Solution:

The original price is $83.33.
(20 percent of the taxes are added to the selling price.)

Solution:

Joey sold 15 ice creams that day.

The fourth kid bought a single ice cream. Therefore, we have the following equation:
Total - (Total / 2 + 1/2) = 1
Solving it, we get the total as 3.

Let's work this method till we reach the first kid.

The first kid bought 15 / 2 + 1/2 = 8 (leaving 7)
The second kid bought 7 / 2 + 1/2 = 4 (leaving 3)
The third kid bought 3 / 2 + 1/2 = 2 (leaving 1)
The fourth kid bought 1 / 2 + 1/2 = 1

Adding all of them together, we get
8 + 4 + 2 + 1 = 15.

Solution:

80

Explanation:
21 B 7 C 9 D 10 A 13
= 21 / 7 + 9 X 10 - 13
= 3 + 90 - 13
= 80

Solution:

The total number of students is 500.

To follow how and why, please see the venn diagram.

Solution:

75km

Explanation:
Distance between Bill and Darren = 40 km
Distance between Bill and Chris + Distance between Chris and Darren = 40 km
Distance between Bill and Chris + (Distance between Bill and Chris - 10) = 40 km
2 * Distance between Bill and Chris = 50 km
Distance between Bill and Chris = 25
Distance between Chris and Darren = 15 km

Therefore, distance between Darren's house and Alex's house = 60 + 15 = 75 km.

Solution:

She had a 50p coin, a 25p coin and four 10p coins.

Solution:

66

Explanation:
The total number of containers required = 9.

5 containers for large jars = 5 * 6 = 30 jars
4 containers for small jars = 4 * 9 = 36 jars

30 + 36 = 66 jars.

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.

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:

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