How is the following worked out?
9 x 9 + 9 / 9 - 9 =

Start from the beginning 9 x 9 is 72
72 + 9 is 81 Then 81 divide by 9 which is 9 then 9 - 9 Is 0
So the answer to that is 0 hope i helped! :) 

Following PEMDAS, it states that you should start with parenthesis first. In this case, there are none, so you find exponents. Again, there isn't any, so you move onto multiplication. And yes, there is. 
Although, keep in mind that if there is multiplication and division, you don't ALWAYS do multiplication first. If there is both multiplication and division just start from the left to the right. 
1) So, the first step to solving this problem is taking 9 x 9 which is 81.
2) The second step would be skipping over to the division and solve 9/9 which is 1. 
3) Now, your equation is 81 + 1 - 9 = 
4) The fourth step to solve this equation is follow pemdas and solve. PEMDAS states that you do addition before subtraction. Although, if there is addition and subtraction at the same equation just go from left to right. 
5) 81 + 1 - 9 = 82 - 9 = 73

The answer would then be 73.