15-(-5)=
And
20-(-12)=

15-(-5)=20

20-(-12)=32

Step-by-step explanation:

1st Problem: 20   2nd Problem: 32

Step-by-step explanation:

When you have two negatives right next to each other, they turn into positives. So, you add instead of subtract.

15 + 5 = 20

20 + 12 = 32

step-by-step explanation:

for the free

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15