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:
[tex]y = 4x + 12.75[/tex]
We insert what x is which in this case is $3
[tex]y = 4(3) + 12.75[/tex]
Order of Operations tells us to multiply first:
[tex]y = 12 + 12.75[/tex]
Now add your values:
[tex]y = 24.75[/tex]
Therefore, Kiyo spent a total amount of 24.75 at Paola's pizza.
Let's check our problem just in case:
[tex]24.75 = 4x + 12.75[/tex]
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:
[tex]24.75 - 12.75 = 12.75 - 12.75 + 4x[/tex]
We are left with:
[tex]12 = 4x[/tex]
We divide:
[tex] \frac{12}{4} = \frac{4x}{4} [/tex]
Our result is:
[tex]3 = x[/tex]
Which checks out because each drink was in fact, $3 dollars as stated in the word problem. Hope that was thorough enough.