Answer:
y = -2x+9
Step-by-step explanation:
To figure out equations of tile patterns simply count the initial value and the rate of change, then convert it into (slope intercept form) which is
y = mx+b
In this case the rate of change is -2x because each figure loses 2 blocks as it goes.
You can also see the the initial figure 1 has 9 blocks so this is our constant
With this information we can create the equation y = -2x+9
m = -2
x = x
b = 9
If more aid is needed a simple search of (Visual Pattern - Writing an Equation and Creating a Table) will help you with a video easily.