You need to provide the last question. There isn’t enough information to help you. I’m sorry
Answer:

Step-by-step explanation:
The question is to simplify the expression 
First, we can eliminate the 2nd parenthesis expression by changing signs of all the terms since there is a "-" sign in front. Then we add the "Like Terms". The process is shown below:

The first answer choices (has some typos) is correct. The correct answer is 
The answer is 15
Hope that helps
To determine the total class the whole class spent, you just have to simply add the individual costs of the three books. Using parenthesis, the solution can be written in the following two ways:
($15 + $9) + $12 = $36
$15 + ($9 + $12) = $36
No matter where you put the parenthesis, the final answer doesn't change. This is because of the Commutative Property of Addition. The order does not matter.
Answer:
Step-by-step explanation:
3 1/5= 3 2/10
4 1/2= 4 5/10
3 2/10+ 4 5/10= 7 7/10