How many of the "Hon Pagoda Stacking Chairs" have been sold in total in the west superstore?
Hon Pagoda Stacking Chairs' is the "Product Name"; west superstore refers to Region = 'West'
SELECT SUM(T1.Quantity) FROM west_superstore AS T1 INNER JOIN product AS T2 ON T1.`Product ID` = T2.`Product ID` WHERE T2.`Product Name` = 'Hon Pagoda Stacking Chairs'