The price of a chair is 55 yuan, and the price of a sofa is 5 yuan more than seven times that of a chair. How much is a chair cheaper than a sofa?
一把椅子售价55元，一张沙发的售价比椅子的7倍还多5元．一把椅子的售价比一张沙发便宜多少元？
<gadget id="calculator">55 * 7</gadget>
<output>385</output>

<gadget id="calculator">5 - 55</gadget>
<output>-50</output>

<gadget id="calculator">385 + (-50)</gadget>
<output>335</output>

<result>335</result>