Answer:
A
Step-by-step explanation:
lets say a slice of pizza = x
can of soda = y
So Kay buys one slice of pizza and one can of soda for $4:
x + y = 4
And Mark buys 6 slices of pizza and 2 cans of soda for $18:
6x + 2y = 18
Now that we have 2 equations we can solve simultaneously using the method of substitution.
1st. x + y = 4
2nd. 6x + 2y = 18
Make x the subject of the formula for equation 1.
x = 4 - y
Substitute in equation 2.
6(4-y) + 2y = 18
Find y.
24 - 6y + 2y = 18
24 - 4y = 18
-4y = -6
y = 1.5
so $1.50 is the can of soda.
Now y is found, it can be used in the 1st equation.
x + 1.5 = 4
x = 2.50
hence, the pizza slice costs $2.50