The school bought 4 sets of tables and chairs, and the total cost was 480 yuan. A table is 80 yuan, how much is a chair?
学校买来4套桌椅，一共用去480元．一张桌子80元，一把椅子多少元？
<gadget id="calculator">480 / 4</gadget>
<output>120</output>

<gadget id="calculator">120 - 80</gadget>
<output>40</output>

<result>40</result>