Which algerbraic expression is not equivalent to 13x + 10

There are no common factors between the two terms
13
x
and
10
- see explanation below.
Explanation:
First, we can try factoring the constants in each term:
13 is a prime number and therefore can only be factored to 1 and 13.
10 can be factored as (1 x 10) or (2 x 5).
Because there are no common factors other than
1
the constants cannot be factored.
And, because there is no
x
in the second term (10), we cannot factor an
x
out of the two terms.
Therefore this expression cannot be factored.