The ratio of males to females in a certain elementary school was 5:7, and 15 females were transferred later. At this time, the ratio of males to females is 2:3. How many males are there in the school?
某小学原来男、女生人数的比是5：7，后来又转来15名女生，这时男、女生人数的比是2：3，学校有男生多少人？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">7 / 5</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">(3/2) - (7/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 / (1/10)</gadget>
<output>150</output>

<result>150</result>