(4) 64 tiles, (5)
, (6) 
Step-by-step explanation:
Given data: Side length of square tile = 1 ft
(4) Side length of square pool = 8 ft


= 64
Hence 64 tiles needed for the border.
(5) Suppose number of square tiles be N and side of square tub is s ft.
So, N = 

So, the expression is
.
(6) The equivalent expression is
.
When reflected across the y axis, the x coordinate becomes the opposite but the y coordinate stays the same, so N is (2, -5)
when reflected across the x axis, the y coordinate becomes the opposite but the x coordinate stays the same, so R is (2, 5)
ANSWER
The solution is

EXPLANATION
The given equations are:

and

We multiply equation 1 by 3 to get,

We multiply equation 2 also by 2 to get,

We subtract equation 4 from equation 3 to get,

This implies that,

We put this value of y into any of the equations say equation 2

Simplify

Group like terms

Simplify,

Divide both sides by 3 to get,

Therefore the solution is

The correct answer is option D.
A door alarm works in 72 out of 100 cases.
surveillance camera works in 68 out of 100 cases.
The probability that method A is used = 72/100
The probability that method B is used = 68/100
Since both method are used we find the probability of A and B
Probability ( A and B) =
* 
=