I don't know how to solve number 19

Example 3 Find (a) the distance between the points P (3 - v5, V7 - 2) and P2(3 + V5, V7 + 2), and (b) the midpoint of the segment joining them. Solution a. P, P2 = VI(3 + V5) - (3 - V5) 12 + 1(V7 + 2) - (V7 - 2) 12 = V(2V5)2 + 42 = V20 + 16 = V36 = 6 b. Find .x: X1+12 _ (3 - V5)+ (3 + 75) 0 = 3 2 2 2 Find J': )'1 + 2 - ( V7 - 2) + (V7 + 2) _ 2V7 V7 2 2 2 .'. the midpoint of PIP2 is the point (3, V7). Find (a) the distance between each pair of points and (b) the midpoint of the line segment joining the points. Express all radicals in simplest form. 16. (6, V7), (4, - V7) 17. ( V6 + 2, V2 - V3), (V6 - 2, V2 + V3) 18. (-r, s), (3r, 5s) 19. (r - s, r + s), (s - r, s + r)