Answer:
Step-by-step explanation:
Let the muffin number = x
Let the pie number = y
x + y = 30 Solve for y. Subtract x from both sides
y = 30 - x
Now calculate the cost
2.5 x + 9 = 4.5 y Substitute for y on the right.
2.5x +9 = 4.5 (30 - x) Remove the brackets.
2.5x + 9 = 135 - 4.5 x Add 4.5 x to both sides
2.5x + 4.5x + 9 = 135 Combine the left.
7x + 9 = 135 Subtract 9 from both sides
7x = 135 - 9
7x = 126 Divide by 7
7x/7 = 126 / 7
x = 18
There were 18 muffins
x + y = 30
18 + y = 30 Subtract 18 from both sides
y = 12
Answer: