Keep in mind PEMDAS(the order of which you solve it is, parenthesis, exponent, multiplication, division, addition, subtraction!)
Start with P(Parenthesis)
A)Well 6+5=11 and 4-1= 3 so 11x3=33
B)12-3=9(here
Where a lot of mistakes happen, you need to keep PEMPAS in mind, D is before A so you need to divid 18/9 before adding 5) so now it is
2+5=7!
C)12+20=32 and 9x2=18 and 18-2=16
Now now the problem is
32/16 which you know is 2!
D)5.2+3.4=8.6 and 8.6x1.5=12.9 which is your answer!
E)6.7-2.7=9.4 and 8.2/9.4=.87
F)2.7+3.1=5.8 and 9.5-5.8=3.7!
These are my personal answers of which were a tad bit rushed through so I would double check and take it with a grain is salt but I hope that this helps!