Use the slope equation:

Plug in the points (2, 15) and (0, -1).

⇒

= 8
The slope of the line is 8.
25%=0.25
24*0.25=6
24-6=18
18 pairs are not black


Solve for y

let's put our equation first

Flip the equation

Now follow the rule of 


_________________________

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add
to both sides

Divide both sides by 


would equal 