I got a maths test today, but I only found out this morning that we have to learn about these, too! And I don't get the second half of this example. We're learning about Quadratic functions (well, slopes and stuff), and this is what the book's example says.

Find, in slope-intercept form, the equation of the line through (-1,3) with a slope of 5.

Then the example goes like this :

y - 3

____ = 5

x - -1

I.E.

y - 3

______ = 5

x + 1

Therefore : y - 3 = 5 (x + 1)

And now, this is the part I don't get.

y + 3 = 5x + 5