Hi!
Slope intercept form is in the form y=mx+b
m is the slope, and that is given so we can plug that into the equation
y = -5x + b
We are also given the y-intercept (0,2) and we can plug that into the equation as well, to find b
2 = 5(0) + b
2 = b
So now that we know both m and b, plug only those two into the equation.
y = -5x + 2
That is your equation