To solve this system of equations, we will first rename the variables to make it easier to work with.

Let x = х, y = ху.

Therefore, we can rewrite the given equations as:
1) y + x = 5
2) y + x - 2y = 13

Simplify equation 2:
x - y = 13

Next, we can solve the system of equations:
1) y + x = 5
2) x - y = 13

Adding the two equations together:
2x = 18
x = 9

Substitute x back into equation 1:
y + 9 = 5
y = -4

Therefore, х = 9 and ху = -4.