This is the answer key of Volume 11-A of the entire set of 12 volumes of word problems solving strategies. If you want to set a solid foundation in math, grasping the techniques on solving word problems is the key to it. This set of books teaches you the techniques and strategies you need to solve word problems. Sample question in this volume: A book is $4.00. If it costs 2/5 as much as a pen, how much does the pen cost? Reasoning and solution: Another way to identify the amount in one whole "As...as" the noun phrase after the second "as" is considered the amount in 1 (whole). From "it costs 2/5 as much as a pen" "a pen" is the noun phrase after the second "as" so the cost of a pen is considered as the amount in 1 (whole). The fractional part is 2/5; the amount in the fractional part is $4.00 so we divide the fractional part, 2/5, into the amount in it, $ 4.00, to find the amount in 1 (whole): 4