Answer:
cost of a burger= $4.5
Cost of soda = $3.5
Cost of a slice of pizza = $5.5
Step-by-step explanation:
Let x = the cost of a burger.
Let y = the cost of a soda.
Let z = the cost of a slice of pizza.
Louis bought a burger and soda for $8. This means
x + y = 8 - - - - - - - -1
Kate purchased a slice of pizza and soda for $9. This means
z + y = 9 - - - - - - - - - 2
David purchased a burger, a slice of pizza, and a soda for $13.50. This means
x + y + z = $13.50 - - - - - - - 3
Substituting x = 8-y and z = 9-y in equation 3, it becomes
8-y + y + 9-y = 13.50
-y -y + y = 13.50 -8-9
-y = -3.5
y = $3.5
Put y = 3.5 in equation 1
x + 3.5 = 8
x = 8 - 3.5 = $4.5
Put x = 4.5 and y = 3.5 in equation 3.
4.5 + 3.5 + z = 13.5
8 + z = 13.5
z = 13.5 - 8 = $5.5
