How can you tell if a function is linear?

Linear functions are usually of degree 1. They are a straight line. y=mx+b

12r - 8 - 12

you have to combine like terms. below i have bolded the like terms:

12r - 8 - 12

together it combines to:

12r - 20

hope this !

i believe it is the square root of 122 because when you turn it on it's side, to where the 5 inches is on the bottom, it looks like it is the same length.