A primary school purchased 18 new sets of desks and chairs, and the total cost was 900 yuan. Each chair was 23 yuan. How much is each desk?
某小学新购买18套桌椅，共花费900元，每把椅子23元，每张课桌多少元？
<gadget id="calculator">900 / 18</gadget>
<output>50</output>

<gadget id="calculator">50 - 23</gadget>
<output>27</output>

<result>27</result>