Find an equation of the line having the given slope and containing the given point. M=4/5,(3,-1)

The equation of the line is y=

start with y = mx + b

y = (4/5)x + b
plug in the point ...
-1 = (4/5)(3) + b
-1 = 12/5 + b
-5 = 12 + 5b ---- I don't like fractions
5b = -17
b = -17/5

y = (4/5)x - 17/5

easier way:
y+1 = (4/5)(x-3)
5y + 5 = 4x - 12
4x - 5y = 17

mold this equation into any form you wish, one of them will be
y = (4/5)x - 17/5