Apizza is cut into 12 pieces. describe the steps you would take to find the area

Π=3.14
r= radius (center of the circle to the outside edge)
A=π
so first you would find the area of the whole pizza
(A=π)÷12
then you would take that area and divide it by 12 
so if the area of the whole pizza is 24
then you would do 24÷12 which would be 2

X = y + 1...so sub in y + 1 for x in the other equation

4x + 3y = -31
4(y + 1) + 3y = -31...distribute thru the parenthesis
4y + 4 + 3y = -31...subtract 4 from both sides
4y + 3y = -31 - 4combine like terms
7y = - 35...divide both sides by 7
y = -35/7
y = - 5

now sub -5 in for y in either of the original equations to find x
x = y + 1
x = -5 + 1
x = -4

solution is (-4,-5)