To find the answer you have to distribute the problem. To do this you do (4×5) and (4×8r). Whenever you do this you get 20+8r+19. You then need to add common factors in which for this problem would be 20 and 19. Whenever you add 20+19 you get 39 and then since the 8 has a r on the side you don't do anything with it so you just put 39+8r and that would be your answer
