If 3a+1.8=7.8, then 1.5a+4=how much.
如果3a+1.8=7.8，那么1.5a+4=多少．
<gadget id="calculator">7.8 - 1.8</gadget>
<output>6</output>

<gadget id="calculator">6 / 3</gadget>
<output>2</output>

<gadget id="calculator">1.5 * 2</gadget>
<output>3</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<result>7</result>