When △=how much, the solution of the equation △+3x=7 is x=1.5.
当△=多少时，方程△+3x=7的解是x=1.5．
<gadget id="calculator">3 * 1.5</gadget>
<output>4.5</output>

<gadget id="calculator">7 - 4.5</gadget>
<output>2.5</output>

<result>2.5</result>