10. 3(6a); a = 3


11. 5d(4); d = -2


12. (5r)(-2); r = -3


13. 3b(8) + (-2)(7c); b = -2, c = 3


14. -4(3s) + 2(-t); s = ½, t = -3


15. 9(4p) - 2(3q) + p; p = -1, q = 4


16. 7(4g) + 3(5h) + 2 (-3g); g = ½, h =⅓