The slope -intercept form of linear equation is y=mx+b.
Where m= slope and b=y-intercept.
Formula to find m is,

The line passes through (-1, 8) and (3, 16) . So, we can plug in x1=-1, y1=8, x2=3 and y2=16 in the above formula. So,



So, m=2
Now we can plug in m=2, x=3 and y=16 in y=mx+b to get the value of b. So,
16=2*3+b
16=6+b
16-6=b
So, b=10.