In algebra, when you are subtracting two terms with the same variable, you can combine the coefficients and keep the variable unchanged.
So, let's take the expression 4a - 3a.
First, we have 4a. This means we have 4 times the variable "a".
Then, we subtract 3a. This means we subtract 3 times the variable "a".
To simplify this expression, we can combine the coefficients of "a". In this case, 4a - 3a can be rewritten as 1a or simply "a".
So, 4a - 3a equals "a".