The price of a math textbook in the school bookshop is $45. If those sold in bookshops outside the school cost 20% less, how much can Peter save by buying from other bookshops rather than the school's if he wants to buy 3 math textbooks?
20% of $45 is (20/100)*$45 = $<<(20/100)*45=9>>9
The price of the textbook in other bookshops cost $9 less than $45 which is $45-$9 = $<<45-9=36>>36
Three textbooks from the school bookshop would cost $45*3 = $<<45*3=135>>135
Three textbooks from another bookshop would cost $36*3 = $<<36*3=108>>108
Peter can save $135-$108 = $<<135-108=27>>27 by buying from another bookshop
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