Yaoyao's family has a monthly balance of 1,200 yuan, which is 60% less than the monthly expenses. How much is the monthly income of Yaoyao's family?
瑶瑶家每月结余1200元，比每月开支少60%．瑶瑶家每月收入多少元？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1_200 / (2/5)</gadget>
<output>3_000</output>

<gadget id="calculator">3_000 + 1_200</gadget>
<output>4_200</output>

<result>4_200</result>