Answer: Variables
F and C are placeholders for numbers. They are called variables because they are allowed to vary, or change. If you change C then it affects F, and vice versa. If the values for the placeholders is not allowed to change, yet it holds a number, then it is considered a constant. In this case, we don't have constants or else the formula isn't too useful.
Answer:

Hope this helps! If you need an explanation, I've got you.
Answer:
$27.59
Step-by-step explanation:
You multiply 30 dollars by 0.85 (1-0.15, with the 0.15 being for the 15 percent off). Which gets you to $25.50, and you then multiply it by 1.082 (the 1.082 being the tax, and the .082 part equating to the 8.2% tax percentage).
Answer:
2x + 4 = 10 = x =3
Step-by-step explanation:
09 - 31 = 0 (the variable x is not present in the given system)
0 +5=6 (the variable x is not present in the given system)
2x + 4 = 10 = x = 3
09-1=4 (the variable x is not present in the given system)
51 - 7 = 1 (the variable x is not present in the given system)
3x + 1 = 9 = x = 8/3
$480 is the price after the discount was added. We can then assume that $480 is 3/4 the price of the original item. To find 1/4, we simply divide by 3, which equals $160. since $160 is one quarter of the price, the original price was $640.