What do you want it to mean. As a variable it can be used for any amount of any substance.
An unknown number
The variable is the letter, the thing that can be changed.
"n" stands for an unknown number.
Igual>>> ALGEBRA
In algebra, there will be letters. Each letter represents a number. Different letters stand for different numbers. e.g. x=1 but y=3. if there are many X's, they all mean the same thing.If there is a number before the letter, you multiply the number by what the letter represents. So 3p means 3*p. This is very simple algebra. I haven't learned complex algebra yet, but i can understand it. But can't explain it well.
An unknown number
The variable is the letter, the thing that can be changed.
It can mean that it is a vector.
"n" stands for an unknown number.
"b" is simply a letter in algebra to replace an unknown number.
d is part of algebra because it is a letter. Any letter in algebra is known as a variable. D is different from d in algebra. They are different.
In Algebra, "is" means Equal (=).
Igual>>> ALGEBRA
In algebra, there will be letters. Each letter represents a number. Different letters stand for different numbers. e.g. x=1 but y=3. if there are many X's, they all mean the same thing.If there is a number before the letter, you multiply the number by what the letter represents. So 3p means 3*p. This is very simple algebra. I haven't learned complex algebra yet, but i can understand it. But can't explain it well.
"And" in algebra usually means addition.
It usually refers to an introductory algebra class.
It mean to Subtract (-)