Anfengtang Primary School bought 8 chairs this year, and spent 640 yuan. They bought 6 desks, and the amount spent was 2.25 times that of 8 chairs. How much is the average desk?
安丰塘小学今年买了8把椅子，用了640元，买了6张办公桌，用的钱数是8把椅子的2.25倍．平均每张办公桌多少元？
<gadget id="calculator">2.25 / 6</gadget>
<output>0.375</output>

<gadget id="calculator">640 * 0.375</gadget>
<output>240</output>

<result>240</result>