10. Given $x, y \in \mathbf{Z}, x>y>0$, satisfying $x+y+xy=80$.
Then the value of $x$ is ( ).
(A) 8
(B) 10
(C) 15
(D) 18
(E) 26
10. E.

From the problem, we have
$$
x y+x+y+1=(x+1)(y+1)=81 \text{. }
$$

Notice that, $x+1, y+1$ are positive divisors of 81. Since $x, y \in \mathbf{Z}, x>y>0$, we have $x+1=27, y+1=9$.
Thus, $x=26$.