4 times a certain number multiplied by 10 2.5, the product is 50, what is the certain number? (solution by equation)
某数的4倍乘以10个2.5，积是50，某数是多少？(用方程解)
<gadget id="calculator">4 * 2.5 * 10</gadget>
<output>100</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>