Concept
Write two equations, one for the total number of Pizzas and the other for the total cost.
Next,
Let a number of cheese pizzas x, and the number of supreme pizzas y.
Total Pizzas = 50
x + y = 50 .................................. (1)
Cheese pizzas cost $10 each, and supreme pizzas cost $12 each.
10x + 12y = 536 ......................................... (2)
Next, from equation 1, make x subject of the formula.
Therefore, y = 50 - x
Hence,
y = 50 - x
10x + 12y = 536
Final answer
Option C
y = 50 - x
10x + 12y = 536