Please help me understand how to get the following computation formula:

The Miracle company had 20,000 units in process on Dec 31, 2020 which was 80% complete as to materials but only 40% complete as to conversion cost. The company records show 40,000 units were transferred to the finished goods inventory during Jan 2021. On Jan 31, 2021, 15000 units were on hand which were 30% complete as to conversion costs and 60% complete as to materials. What are the equivalent units of production for the conversion costs in Jan, assuming Miracle uses FIFO?