1. C=2πr
We need to move r by itself on a side of the equation.
Divide both sides of the equation by 2π. This will cancel out the side with the r.
r=C/2π
2. A=1/2*b*h
Divide both sides by 1/2*h, isolating b
b=A/h
3.y=mx+b
Now we have to do reverse PEMDAS, we have to add/subtract before we can multiply or divide to simplify.
Subtract both sides by b
y-b=mx
Now divide both sides by m
x=
Remember we have to divide both terms y and -b by 2, so it goes on the bottom for both.