To find the equation of a line, you first have to find the gradient, which is 1--1 / -3-3
So, the gradient is -1/3
Then, substitute one five point into he equation y-y1= m(x-x1) (where m is the gradient)
sub (3,-1)
y+1= -1/3(x-3)
Expand the brackets
y+1= -1/3x+1
Take 1 to the other side as a negative number
So, the line's equation is y=-1/3x
