The owner of a photocopy store charges 7 cents per copy for the first 100 copies and 4 cents per copy for each copy exceeding 100. In addition, there is a setup fee of $2.50 for each photocopying job.

(a) Determine R(x), the revenue from selling x copies.

(b) If it costs the store owner 3 cents per copy, what is the profit from selling x copies? (Recall that profit is revenue minus cost.)