Idont understand how would i solve this

Subtract (x+109) from 180; the result is 71-x.  The reason for doing this is that we want to equate "corresponding angles."  71-x and x+89 are corresponding angles.  Set them = to one another and then solve the resulting equation for x:

71-x = x+89
-18 = 2x, so x = -9

Now let's determine the angle x+89.  Since x=-9, that angle is 80 (degrees).