The equation of a line is typically written as 'y=mx+b' where 'm' is the slope and 'b' is the y-intercept.

So, in your case m = 4.

We will find 'b' by plugging in the values for 'x = 1' and 'y = -1' since the line goes trough (1, -1), we well as for 'm = 4':

-1 = 4*1 + b

4 + b = -1

b = -1 - 4

b = -5

The equation of the line is:

y = 4x - 5