A chair is 90 yuan, and you can buy 3 chairs for the price of 1 desk. How much does it cost to buy a set of office furniture (a table and a chair).
一把椅子90元，买1张办公桌的钱可以买3把椅子．买一套办公桌椅(一张桌子和一把椅子)需要多少元．
<gadget id="calculator">90 * 3</gadget>
<output>270</output>

<gadget id="calculator">90 + 270</gadget>
<output>360</output>

<result>360</result>