In a math test in a certain class, there are 42 people who got the first question right, and 48 people who got the second question right. In this class, each of the 60 people got at least one question right. What is the percentage of the number of people who got both questions right? ．
某班数学测验，做对第一题的有42人，做对第二题的有48人，这个班60人每人至少做对一道题，那么两题全对的人数占全班人数的多少．
<gadget id="calculator">48 - 60</gadget>
<output>-12</output>

<gadget id="calculator">42 + (-12)</gadget>
<output>30</output>

<gadget id="calculator">30 / 60</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>