During the Spring Festival, supermarkets purchased 540 small Chinese knots, 60 less than four times the purchase of large Chinese knots. How many large Chinese knots were purchased? (solution by equation)
春节期间超市购进540个小中国结，比购进大中国结的4倍少60个，购进大中国结多少个？(用方程解)
<gadget id="calculator">60 + 540</gadget>
<output>600</output>

<gadget id="calculator">600 / 4</gadget>
<output>150</output>

<result>150</result>