Measure of Each Interior Angle?

The Question says: Find the measure of each interior angle of Pentagon ABCDE. The measures are A=3z, B=4z, C=5z, D=3z, E=5z. How would you find the interior angle? I THINK the formula has something to do with (n-2)180 but I'm not sure please give me step by step instructions I really don't understand this!! :(