The number of the school chorus is between 60 and 70. The ratio of boys to girls is 5:4. How many boys are there in the chorus?
学校合唱队人数在60至70人之间，男生与女生的人数比是5：4，合唱队有男生多少人．
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

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

<gadget id="calculator">63 * (5/9)</gadget>
<output>35</output>

<result>35</result>