Answer:
y = -2x +15
Explanation:
The point-slope form of the equation for a line through (h, k) with slope m is ...
... y - k = m(x - h)
For your point (h, k) = (5, 5) and slope m = -2, the equation in point-slope form is ...
... y - 5 = -2(x - 5)
Simplifying, we get
... y - 5 = -2x +10
Adding 5 puts the equation into slope-intercept form, as you want.
... y = -2x +15