The ratio of the numbers A and B is 3:4, the number B is 100, what is the number A?
甲乙两数的比是3：4，乙数是100，甲数是多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">100 * (3/4)</gadget>
<output>75</output>

<result>75</result>