Need Help With This Emma y = 10 - 2x is not a linear function because the graph below has a negative rate of change

Georgia y = 10 - 2x is a linear function because it can be written in the form

y = mx + b

y = 10 - 2x

y = 10 + (-2x)

y = 2x + 10

Who Is Correct and Why?
(also i suck at drawing, don't judge me)