Consider a stylized production process that involves two steps. Step A has a processing time of $1$ minute per unit; no setup is required. Step B has processing time of $0\mathrm{.}1$ minutes per unit, but a setup time of $9$ minutes is required per batch. Suppose units are produced in batches of $15($i$.$e$.,$ after each set of $15$ units are produced, Step B must incur a setup of $9$ minutes$).$ What is the capacity of the process $($in units per minute$)?$