Will give brainliest if correct.

Answer:
y=-3x+4
Step-by-step explanation:
To find the equation y=mx+b, we need to find b. We already have m, which is the slope. m=-3
To find b, we can plug in the point (3,-5) into the equation y=-3x+b
3 is x and -5 is y
-5=-3(3)+b
simplify
-5=-9+b
b=4
So, now we put b=4 into the original equation, and we get y=-3x+4