Algebra: please answer #2

Y=mx+b
m=slope
b=y intercet

so find the slope
slope is found by (y1-y2)/(x1-x2)
the points are (1,-1) and (5,7)
(x,y)
x1=1
y1=-1
x2=5
y2=7
subsitutte
(-1-7)/(1-5)=-8/-4=4/2=2
the slope is 2
y=2x+b
solve for b by subsituting one fo the points
try (1,-1)
x=1
y=-1
-1=2(1)+b
-1=2+b
subtract 2 form both sides

-1-2=b
-3=b
y=2x-3
the answe ris y=2x-3,
the answer is the third one from the top
y=2x+3