Guy me to slove the problem. i know the answer is b but how this is b.

1/2 (x + 9)= 3
1/2x + 9/2 = 3
1/2x = 3 - 9/2
1/2 x. = 3 - 4 1/2
1/2 x = -1 1/2
x = - 1 1/2 ÷ 1/2
x = -3/2 ÷ 2/1 = -6/2 = -3

Answer:

13.46

step-by-step explanation:

16.80 x .20 = 13.46