Yucai Primary School has 50 fewer boys than the whole school (4/7), and 30 more girls than the whole school (4/9). How many people are there in the whole school?
育才小学男生比全校人数的(4/7)少50人，女生比全校的(4/9)多30人，全校有多少人？
<gadget id="calculator">50 - 30</gadget>
<output>20</output>

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

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(4/9) - 1</gadget>
<output>-5/9 = around -0.555556</output>

<gadget id="calculator">(4/7) + (-5/9)</gadget>
<output>1/63 = around 0.015873</output>

<gadget id="calculator">20 / (1/63)</gadget>
<output>1_260</output>

<result>1_260</result>