y = 7x - 48
use slope formula so, y2 - y1 over x2 - x1 to get your m value or your slope which is 7. then plug in the slope and a random set of point so I used (6, -6). -6 = 6(7) + b, simplify.
-6 = 42 + b, subtract 42 which leaves you with b= -48. hope this helps :)