The number of students in a certain class is between 40 and 50. It is known that the ratio of males to females is 5:4. How many males are there in this class?
某班人数在40～50人之间，已知男、女生人数比是5：4，这个班男生有多少人．
<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">45 * (5/9)</gadget>
<output>25</output>

<result>25</result>