Does this picture show the diameter or radius of a circle?

Radius

Step-by-step explanation:

a line segment extending from the center of a circle or sphere to the circumference or bounding surface

the diameter is 18 inches

y=−9/2x+10

step-by-step explanation:

let's solve for y.

0−9x−2y=−20

step 1: add 9x to both sides.

−9x−2y+9x=−20+9x

−2y=9x−20

step 2: divide both sides by -2.

−2y

−2

=

9x−20

−2

y=

−9

2

x+10

i'm not sure i quite understand, could you provide more information?