The ratio of the numbers A and B is 5:3, and the number B is 45. What is the number of A?
甲、乙两数的比是5：3，乙数是45．甲数是多少．
<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">45 * (5/3)</gadget>
<output>75</output>

<result>75</result>