Marilyn wants to buy a pair of boots online. On Amazon.com, the boots cost $16 and shipping costs $4. On eBay, those same pair of shoes are only $13, but shipping costs twice as much as it does on Amazon. How much more expensive do the boots work out to be on eBay?
The total cost on Amazon.com is $16 + $4 = $
<gadget id="calculator">16+4</gadget>
<output>20</output>
20.
Shipping on eBay costs $4 x 2 = $
<gadget id="calculator">4*2</gadget>
<output>8</output>
8.
The total cost on eBay is $13 + $8 = $
<gadget id="calculator">13+8</gadget>
<output>21</output>
21.
The boots cost $21 - $20 = $
<gadget id="calculator">21-20</gadget>
<output>1</output>
1 more on eBay.

<result>1</result>