Question

simplification of 54 ÷3 of 6+9

Answer 1

54 ÷ 3 of 6 + 9 

Using BODMAS 

B - Bracket 
O - Of
D - Division 
M - Multiplications
A - Addition
S - Subtraction

Firstly solve of
it also means product (multiplication)
54÷18+9

then solve division
3+ 9

12 is answer  

Answer 2

Solution using BODMAS:

Brackets of division multiplication addition subtraction.

54÷3 of 6 + 9
= 54÷18 + 9
= 3 + 9
= 12