cost accounting

hi this question was anweread at ready but i don't understan where they come out with the manufacturing overhead on the first question, because this problem it doesn't have it...can you help

\begin{tabular}{|l|r||} \hline Calculation of Selling Price of "B" per unit & \\ \hline \hline Particulars & Amount ($) \\ \hline \hline Direct Materials & 60 \\ \hline \hline Direct Labor (3 hours $12) & 36 \\ \hline \hline Manufacturing Overheads (3 hours $93) & 279 \\ \hline \hline Total Cost & 575 \\ \hline \hline(+) Desired Profit (40% on Cost) & 150 \\ \hline \hline Selling Price per unit of "B" & 525 \\ \hline \end{tabular} Lennox Industries manufactures two products: A and B. A review of the company's accounting records revealed the following per-unit direct costs and production volumes: Manufacturing overhead is currently computed by spreading overhead of $1,860,000 over 20,000 direct labor hours. Management is considering a shift to activity-based costing in an effort to improve the firm's Lennox determines selling prices by adding 40% to a product's total cost. Required: A. Compute the per-unit cost and selling price of product B by using Lennox's current costing procedures