3*x
3*2
3x+6
5*x
5*-8
5x-40
Story short the answer is 25
If your looking for a simplified answer, it would be

.
Hope this helps.
The temperature would be -7 degrees
15. 
Step 1: Distribute the subtraction sign to all the numbers in the second set of parentheses...


Step 2: Combine like terms (
's go with
's)




Step 3: Combine like terms (
's go with
's)




Step 4: Combine like terms (normal numbers go with normal numbers)

1 + 2
3

You were correct!
16. 
I don't really know how to explain this one but I got: (7m-6n)(7m-6n)