There are 720 students in a certain school, the ratio of the number of boys to the number of girls is 5:4, how many boys are there?
某校有学生720人，男生人数和女生人数的比是5：4，男生有多少人？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">720 * (5/9)</gadget>
<output>400</output>

<result>400</result>