The answer would be A. m= -3/5 and b=-4/5
"m= -5-1 divided by 7--3
or, -6/10
or, -3/5.
to find the (B)
(-3,1). y=mx+b or 1=-3/5 × -3+b, or solving for b: b=1-(-3/5)(-3). b=-4/5.(7,-5). y=mx+b or -5=-3/5 × 7+b, or solving for b: b=-5-(-3/5)(7). b=-4/5.See! In both cases we got the same value for b. And this completes our problem.The equation of the line that passes through the points(-3,1) and (7,-5)isy=-3/5x-4/5"
Source: webmath