she has 18 bottles, when you divide it by two, she could give two bottles to 9 people. but, she only wants to give it to 6 friends. meaning that she would be left with 3 pairs of bubbles. as in, 6 bottles.
Point-slope form is y - y_1 = m (x - x_1) where x_1 and y_1 are the given coordinates and m is the slope. When you plug the given values into the equation you get y - 3 = 6 (x - 8) .