Answer:
13. -20x
14. 10x + 9y
15. 12x + 48y
Step-by-step explanation:
13. multiply
14. and 15. use the distributive property
13. -5(4x) = -20x
-5*4x = -20x
14. 7x + 9y + 3x = 10x + 9y
7x + 3x = 10x
15. 6(2x + 8y) = 12x + 48y
6*2x = 12x
6*8y = 48y
