Triple Play Inc., which produces basketballs, has two departments: cutting and stitching. The cutting department uses a synthetic material to make the outside covering of the ball.

Basketballs that have undergone the cutting process are immediately transferred to the stitching department. Stitching department uses three types of materials: Rubber to make the balloon that holds air, Nylon used to make the stuffing and foil is used to imprint label information. Rubber is added at the start of the process, Nylon is inserted into the ball when the ball is 70% complete, and Foil is used to imprint Helmers name on the finished ball and is added at the end of the process.

Conversion costs are added evenly during stitching operations. When those operations are done, the basketballs are immediately transferred to Finished Goods.

On May 1, 2017, Helmer had 100 balls in inventory (40% complete). During May, Helmer put another 100 balls into production. At the end of May, Helmer was left with 80 balls that were 50% complete.

Under the FIFO method of process costing, compute equivalent units of work done for Rubber for the month of May.