This is just y=mx+b in simplified terms.
The traditional way would be written as:

Since the slope and the y-intercept both have the same denominator, you can put it under (x-5)
Since there is an understood 1 in front of x, it is still treated as
.
Since the y-intercept is positive
, you can change them both to negative and it will be positive.
I know this explanation is confusing, but it is rarely seen like this. Just understand that it is equivalent.