Column calculation: subtract 7.5 from 3 times a number to get 0, what is this number? (solution by equation)
列式计算：一个数的3倍减去7.5得0，这个数是多少？(用方程解)
<gadget id="calculator">7.5 + 0</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 / 3</gadget>
<output>2.5</output>

<result>2.5</result>