One question at a time, please. I will focus on #16 and ignore #18.
slope: 3/4 line passes thru (-8,2)
Write out y = mx + b. Subst. 2 for y. Subst. -8 for x Subst. (3/4) for m:
2 = (3/4)(-8) + b. Find b. 2 = -6 + b => b = 8
So your equation is y = (3/4)x + 8. Please, use ( ) around those fractions!