Answer:
y = -2x + 9
Explanation:
The general shape of the equation is y = ax + b, you just have to find a and b.
b is simple, it is the y coordinate where the line crosses the y axis, i.e., b=9.
a is the slope of the line. This is the change in y when you take one step to the right. The change is -2.
Hence y = -2x + 9