Answer
$$6x - (-5x)$$
or
$$11x$$
Work Step by Step
We need to translate the different parts of the statement in order to put together an expression.
"The difference between" means to subtract.
"$6$ times a number" means "$6x$."
"$-5$ times a number" means "$-5x$."
Now, we can put together the expression:
$$6x - (-5x)$$
Simplify:
$$6x + 5x$$
Add:
$$11x$$