James wants to build a 16-foot by 20-foot quilt.  He uses patches that are each 4 square feet.  The first 10 patches cost $10 each and then each patch after that cost half as much.  How much do the patches for the quilt cost?
The patch is 16*20=
<gadget id="calculator">16*20</gadget>
<output>320</output>
320 square feet.
So he needs 320/4=
<gadget id="calculator">320/4</gadget>
<output>80</output>
80 patches.
The first 10 patches cost 10*10=$
<gadget id="calculator">10*10</gadget>
<output>100</output>
100.
He gets a discount on the next 80-10=
<gadget id="calculator">80-10</gadget>
<output>70</output>
70 patches.
They each cost 10/2=$
<gadget id="calculator">10/2</gadget>
<output>5</output>
5.
So in total they cost 70*5=$
<gadget id="calculator">70*5</gadget>
<output>350</output>
350.
That means in total he paid 100+350=$
<gadget id="calculator">100+350</gadget>
<output>450</output>
450.

<result>450</result>