n+m
3n + 15 equals 3 times the number n, the answer to which is increased by 15. It can only be evaluated if the value of n is known. The expression can be factorised but that is of marginal help in evaluating it.
n + 6.2
If you mean 2n+4, or 2n-4, that already is an algebraic expression. The idea might be to put it into words. 2n+4 is twice n, increased by 4. Notice you need a comma because if you write twice n increased by 4 this is 2(n+4)
n + 25 =====
8+n
n/6 + 3
-8 + 13/N, where N ≠0.
n+7 or X+7
n+81
Un = n + 32
If you call the number "n", then the expression would be "n+5".
nineteen
31 plus n
Nineteen is spelled as N-I-N-E-T-E-E-N.
n + [(n - 19) - 3] = 2n - 22
n+m