So for the equation im going to be using the slope-intercept form

where the m variable is the slope and the b variable is the y-intercept.
Since we already know the slope, 3, we can use it to replace the m variable, but we still need to solve for b. And to do so, we will need to replace the x and y variable with 4 and -7 since we know that the line passes through that coordinate.

multiply 3 and 4 to make 12.

subtract 12 from each side to get

and now that we know b, we can format the equation as

.