A percentage is an amount out of 100. You have an amount out of 200, divide by two and there's your answer.
12:200 divided by 2
6:100
6%
5 and 1/5 of cake because the difference of 8 and 1/10 and 2 and 9/10 is 5 and 2/10 or 5 and 1/5
21x + 28 = 156 - 2
21x = 154 - 28
21x/21 = 126/21
X = 6
