In the formula C = 2r, C stands for

We can't tell. Any certain letter doesn't have to mean the same thing wherever you see it. You can use any letter you want to represent any quantity you want when you write an expression or a formula, as long as you clearly tell what it stands for.

C = 2r This could mean anything.

It could mean that Julie has a great many pets. For every rat she has,

she also has two cats. Write a formula that tells how many cats she

needs for 16 rats.

It could mean that the Circumference of a circle is equal to 2 times

the length of the circle's radius.

It could mean that Rocko is baking oatmeal-raisin cookies. He is

cutting each raisin in half, and putting 1/2 of one raisin in each cookie.

Write a formula that tells how many cookies he can make with 16 raisins.