Slope intercept form is 
where
is the slope
and
is the y-intercept
they give us that the slope is 2
so our
then to find , we temporarily plug in the point they gave us for x and y
so
and solve for
3 = 2 + b
1 = b
so our
put this together and we get
as our answer
where
and
they give us that the slope is 2
so our
then to find
so
and solve for
3 = 2 + b
1 = b
so our
put this together and we get