156 dollars because 13 times 12 (months)
equals 156
45 of a number refers to 180, and 54 refers to 216. So 100 of a number is 400 and 1 of a number is 4. If 54x - 45x = 36, just plug in 4 and double check: 54(4) - 45(4) = 36 or 216 - 180 = 36, which is true.
A or b depending on wich way your moving
Average = Mean
To find the mean, add up the numbers and divide it by how many numbers there are.
So,

There are 5 numbers in total.

To do these types of division, ignore the decimal and add a 0 at the end.
So we can do:

And put back the decimal.
Hope this helps :)
Answer:
you're correct it's scale factor