i chose a number less than 20 divided it by 2 and then add 6 i then divide this result by 3 and my answer is 4.5 what number am i

Question

what did I start with 

Answer 1

number = n

 

divided it by 2 = n/2

 

add 6 = n/2 + 6 = (n+12)/2

 

divide result by 3 = (n+12)/2 ÷ 3

 

                          =( n+12)/2 * 1/3 = (n+12)/ 6

 

answer is 4.5

 

(n+12)/ 6 = 4.5

 

n+12 = 27

n= 15