A project is completed in 15 hours by A and B, and by B and C in 20 hours. Now A works for 32 hours, and A and C cooperate for another 3 hours. How many hours does A work alone?
一项工程，甲乙合作15小时完成，乙丙合作20小时完成，现由甲先做32小时后，甲丙又合作了3小时才完成，甲单独做多少小时完成？
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / (1/40)</gadget>
<output>40</output>

<result>40</result>