There are 90 students in the sixth grade in a certain school, including 56 boys (4/7) and girls (2/3). How many boys are there in this grade?
某校六年级有学生90人，其中男生人数的(4/7)与女生人数的(2/3)共56人，这个年级的男生有多少人？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 90</gadget>
<output>60</output>

<gadget id="calculator">60 - 56</gadget>
<output>4</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(2/3) - (4/7)</gadget>
<output>2/21 = around 0.095238</output>

<gadget id="calculator">4 / (2/21)</gadget>
<output>42</output>

<result>42</result>