One week, Huang ordered 1 pizza and 2 sodas for $12. The next week, he ordered 3 pizzas and 4 sodas from the same restaurant for $30. Write and graph a system of equations to determine the cost of each pizza and the cost of each soda from this restaurant.
Let x = the cost of a pizza
Let y = the cost of a soda

Question

anonymous · Answer

x = $ 6
y = $ 3

anonymous · Answer

x+2y=12
3x+4y=30
Put them in slope intercept form:
2y=-x+12
y=-1/2x+6
4y=-3x+30
y=-3/4x+15/2
Now graph both and you will find that they intersect at (6,3)
This means $6 for pizza and $3 for soda.

anonymous · Answer

System of equations:
1x + 2y = 12
3x + 4y = 30
Solving for x
x = -2y + 12
Substituting, 
3(-2y + 12) + 4y = 30
-6y + 36 + 4y = 30
-2y = -6
y = 3
Substituting again,
x = -2(3) + 12
x = -6 +12
x = 6
Answer
x = $6, y = $3