Cullumber Co$.$ has zero units of beginning work in process. During the period, $15,360$ units were completed and transferred out, and there were $640$ units of ending work in process one$-$fifth complete as to conversion cost and $100\%$ complete as to materials cost. What were the equivalent units of production for $($a$)$ materials and $($b$)$ conversion costs?

$($a$)$ Materials

units

$($b$)$ Conversion costs

units