There are 3 ways of solving a simultaneous problem, substitution method, elimination method and Gauss-Jordan method. I'm gonna use the substitution method since it's easier and i think it would suit your level more.
First let's try solving for y since it's easier to start with.
Firstly we have to find an equation for x:

Great, now we can use the substitution method to find the value of y using the first equation:

Now we know that y=1 we can solve the first equation we made:

And the answer is 
Double check:

And that's our final answer! (4,1)
Answer:
2x - 19
Step-by-step explanation:
Perimeter = sum of sides
First let's simplify each side
We can simplify each side by using distributive property. Distributive property is where you multiply the number on the outside of the parenthesis by the numbers on the inside of the parenthesis.
2(x + 5)
Distribute by multiplying x and 5 by 2
2 * x = 2x and 2 * 5 = 10
2x + 10
1/2(4x + 8)
Distribute by multiplying 4x and 8 by 1/2
1/2 * 4x = 2x and 1/2 * 8 = 4
2x + 4
-3(2x + 11)
Distribute by multiplying 2x and 11 by -3
-3 * 2x = -6x
-3 * -33
-6x - 33
Finally add all the simplified expressions ( remember that they represent the side lengths of the triangle )
2x + 10 + 2x + 4 - 6x - 33
Combine like terms
2x + 2x - 6x = -2x
10 + 4 - 33 = -19
Perimeter: -2x - 19
We are given coordinate of K point (7,4).
We need to find the new coordinate of K' point.
Given rule is K' = Ro 270°^(k).
That represents rotation of k 270 degree about the origin.
<em>The rule for rotation of 270 degree about the origin is as following:</em>
<em>(x, y) --------> (y, -x).</em>
Now, applying same rule on point (7,4).
(7,4) -----------> (4,-7).
<h3>Therefore, the coordinates of k' is (4,-7).</h3><h3>Correct option is A. (4,-7).</h3>
In a fraction, the number below the line (called the denominator) represent the whole. In this problem '8' is in the denominator and represents the 8 slices of pizza there were to start with
Answer=8 slices
The answer would be a hope it helps