In this question, we will use slope intercept form that is y=mx +b, where m is the slope and b is the y intercept .
For the given question . x=1, y=-1 and slope , m = -5
We need to substitute these values in slope intercept form and solve for b, that is
-1=-5(1)+b
-1 = -5+b
Adding 5 to both sides
b =4
So we have slope, m =-5 and b=4
THerefore required equation is
y=-5x+4