Okay, it's wrong because they forgot to do -2 times 3x.
The correct answer is

-2x-8
Hope i got is correct!
For number 3 add all the numbers and divide how numbers you have
The answer is for this question is 4/5
Most of those are correct but the ones that are not are, (15+8 divided by 4-6) as division comes first. 6x3-8 as multiplication comes before subtraction. And 2/3+4x2, multiplication comes before addition. So change those couple up and you got it.
2 hope that helps have a great day