Use substitution to solve the system.
X = 2y +6
2x + 5y = 3

The answer is explained below.

Step-by-step explanation:

As stated, Juan ordered 20 pizzas; 45% of the pizzas has 8 slices: 45%*(20) = 45/100*(20) = 45/10*(2) = 90/10 = 9 pizzas.

On the other hand, he also ordered 55% of pizzas with 12 slices: 55%*(20) = 55/100*(20) = 55/10*(2) = 110/10 = 11 pizzas.

So we have 9 pizzas with eight slices and 11 pizzas with twelve slices, to get the total amount of pizza slices, it is necessary to do the following: (9) (8) + (11) (12) = 72+132 = 204 slices.