Answer:
Step-by-step explanation:
Distributive property:
a(b-c) = a*b + a*-c = ab-ac
13.- 11(s+9) = 11*s + 11+9 = 11s+99
14.- -21(x-7) = -21*x -21*-7 = -21x + 147
15.- 13(20-a) = 13*20 + 13*-a = -13a + 260
16.- -8(17+b) = -8*17 -8*b = -8b - 136
17.- (r+1.68)(-0.1) = -0.1(r+1.68) = -0.1*r - 0.1*1.68 = -0.1r - 0.168
18.- 3.25(5.02-t) = 3.25*5.02 + 3.25*-t = -3.25t + 16.315
