Xiao Ming and Xiao Gang bought a total of 25 exercise books. If Xiao Gang buys 5 more, then (1/2) of Xiao Ming’s exercise books is exactly equal to (1/3) of the number of Xiao Gang’s exercise books. How many books did Xiao Ming originally buy? excercise book.
小明和小刚共买了25本练习本，如果小刚再买5本，则小明练习本的(1/2)正好与小刚练习本数的(1/3)相等，小明原来买了多少本练习本．
<gadget id="calculator">25 + 5</gadget>
<output>30</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">30 * (2/5)</gadget>
<output>12</output>

<result>12</result>