In a parallelogram KLMN, angle K = 3x + 18 degrees and angle L = 5x − 12 degrees. Find the measure of each interior angle.

$$(5x - 12) + (3x + 18) = 180$$ $$8x + 6 = 180$$ $$8x = 180 - 6$$ $$8x = 174$$ $$x = \frac{174}{8}$$ $$x = 21.75$$

Step 3: Calculate the size of each interior angle.
Substitute $x = 21.75$ into the expressions for $\angle N$ and $\angle M$.

$$\angle N = 5x - 12^\circ = 5(21.75) - 12 = 108.75 - 12 = 96.75^\circ$$ $$\angle M = 3x + 18^\circ = 3(21.75) + 18 = 65.25 + 18 = 83.25^\circ$$

In a parallelogram, opposite angles are equal.

$$\angle K = \angle M = 83.25^\circ$$ $$\angle L = \angle N = 96.75^\circ$$

The interior angles are:

$$\angle K = \boxed{83.25^\circ}$$ $$\angle L = \boxed{96.75^\circ}$$ $$\angle M = \boxed{83.25^\circ}$$ $$\angle N = \boxed{96.75^\circ}$$