A 30 cm ruler that weighs 52 g is balanced on a finger.

At the 30cm mark, a pen, weighing ___ g is placed.

The ruler is balanced on the finger at 18cm.

Using Newton's Second Law of Rotational Motion, write out the equation for the diagram. Note that you can place actual numbers in for the left and right center of masses of the stick, the mass stick on the left and right of your finger.. Using these values, solve for the mass of the pen.