The ratio, simplify it
12shirts:6jeans
12/6=2/1
or
2shirts:1jean
18shirts
18/2=9
2shirts times 9=18shirst
2shirts:1jean times 9:9=18shirts:9jeans
answer is 9 pairs of jeans
For Commutative Property of Addition
Let us take a decimal number
and a fraction 
Now, according to the Commutative property of Addition:
For any two numbers
and
:

So, for
and 
Let us add


Also,


Therefore, 
Hence, Commutative Property of Addition is satisfied.
For Associated Property of Addition
Let us take two same decimal numbers
,
and a fraction 
Now, according to the Associated property of Addition:
For any three numbers
,
and 

So, for
,
and 
The Left hand side:







The Right hand side:






Thus,

Therefore, 
Hence, Associative Property of Addition is satisfied.
Okay so for number 3, you have to do the top work first.
3: POSITIVE 2!! first, you do the stuff inside the parentheses first because of P(parentheses)EMDAS. so, 14-2-10! -2-10 is -12 and then plus positive 14 is +2. but, the negative sign outside of the parentheses makes that +2 a -2.
but, you cant forget the -12 outside. you have to do -12-2 which gets you -14. then, this is easy! -14 divided by -7 is a positive 2!
5: POSITIVE 3!! again, do the stuff in the parentheses first!! -2-4 is -6. then, -6 x 2 is -12! so, divide -12 by -4 and you get a positive 3!
If you notice, the container is really just two circles, with a diameter of 4 each, and a square with sides of 10.5.
now, if we just get the area of each circle, keeping in mind their radius is half of the diameter, namely r = 2, and get the area of the 10.5x10.5 square, sum them up, that'd be the surface area of the container.