Answer:
30
Step-by-step explanation:
(-) (-) = +
Therefore 15 - (-15) = 15 + 15 = 30
I hope you can read this, and I hope you understand how I did 7. I probably overworked it, and it was possibly a simpler way to get it.
She has more than enough because with 8 cups you only need 2 quarts. She has 3 which gives her 12 cups.