There are 45 students in Class 6 and 2. Now there are two kinds of magazines to subscribe to. Each person must subscribe to at least one of them. (4/5) of the students subscribe to the English newspaper, and (2/3) the students subscribe to the Mathematical Journal. Both newspapers are subscribed. How many classmates are there?
六二班有45名同学，现在有两种杂志要订，每人至少定一样其中(4/5)的同学订阅英语报，(2/3)的同学订阅数学报，两种报纸都订阅的同学有多少？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">45 * (4/5)</gadget>
<output>36</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">45 * (2/3)</gadget>
<output>30</output>

<gadget id="calculator">36 + 30</gadget>
<output>66</output>

<gadget id="calculator">66 - 45</gadget>
<output>21</output>

<result>21</result>