$$\begin{aligned} & A = \left\{ n \in Z ^ { + } \mid n \leq 100 ; n \text{ is divisible by } 3 \right\} \\ & B = \left\{ n \in Z ^ { + } \mid n \leq 100 ; n \text{ is divisible by } 5 \right\} \end{aligned}$$
The sets are given. Accordingly, how many elements does the difference set $\mathrm { A } \backslash \mathrm { B }$ have?
A) 33
B) 32
C) 30
D) 28
E) 27

In the following table consisting of 100 unit squares numbered from 1 to 100, some squares will be painted.

1	2	3	$\ldots$	10
11	12	13	$\ldots$	20
.	.	.		.
.	.	.		.
.	.	.		.
91	92	93	..	100

Squares with even numbers are painted yellow, squares that are multiples of 3 are painted red, and squares that are multiples of 5 are painted blue.
For a square to be orange, it must be painted only yellow and red.
Accordingly, how many unit squares in the table are orange?
A) 8
B) 12
C) 13
D) 15
E) 18

When 6 of the integers from 1 to 9 are placed in the boxes below such that each box contains a different number, all equalities are satisfied.
$$\begin{aligned} & \square + \square = 5 \\ & \square - \square = 5 \\ & \square : \square = 5 \end{aligned}$$
Accordingly, what is the sum of the unused integers?
A) 23
B) 21
C) 19
D) 17
E) 15

A three-digit natural number whose digits are different from each other and from zero is called a middle-divisible number if the digit in the tens place divides the digits in the other places. For example, 428 is a middle-divisible number. Accordingly, what is the difference between the largest middle-divisible number and the smallest middle-divisible number?
A) 723
B) 727
C) 736
D) 742
E) 745