There are 900 students in a certain school, of which the number of girls is 80% of that of boys. How many girls are there?
某校共有学生900人，其中女生人数是男生的80%，女生有多少人．
<gadget id="calculator">80 + 100</gadget>
<output>180</output>

<gadget id="calculator">80 / 180</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">900 * (4/9)</gadget>
<output>400</output>

<result>400</result>