Y = total amount of money spent
x = cost of one drink
So our expression is:
4x + 12.75
4x stands for 4 drinks times x price of one drink
The 12.75 is a one time fee for the pizza, since Kiyo isn't buying multiple pizzas.
The problem also asks us to find the total price, so we write an equation:

We insert what x is which in this case is $3

Order of Operations tells us to multiply first:

Now add your values:

Therefore, Kiyo spent a total amount of 24.75 at Paola's pizza.
Let's check our problem just in case:

Since we now know what y is equal to, we can plug that into our original equation and check just to verify
We should subtract 12. on both sides of the equation because of inverse operations:

We are left with:

We divide:

Our result is:

Which checks out because each drink was in fact, $3 dollars as stated in the word problem. Hope that was thorough enough.
7 + (0-7) * 2/3 = 7 - 14/3 = (21 - 14) / 3 = 7/3 = 2.3
I don’t really understand for question 11 to 13
Answer:
Option (b) is correct.

Step-by-step explanation:
Given: 
We have too choose the correct simplification for the given statement.
Consider 
Using property of exponents,
We have,

Again applying property of exponents 
We have,

Simplify, we have,

we get,

Thus, 
Option (b) is correct.