What is the radius of a circle. =units

The circumference is the outside perimeter of a circle. It's the distance around a circle. A radius can be a line from any point on the circumference to the center of the circle. If you put two radii together, edge to edge, going through the center of a circle, you would get a diameter.

Step-by-step explanation:

Use substitution
Given both y values, you know that they have to be equal

3x + 3 = x - 1
2x + 3 = -1
2x = -4, divide by 2
x = -2
Now plug x value into any of the equation to find y value
y = 3(-2) + 3
y = -6 + 3, y = -3

Solution: x = -2, y = -3