It is known that a=1.8b=2.5; then what is the value of 4a+2b.
已知a=1.8b=2.5；那么4a+2b的值是多少．
<gadget id="calculator">4 * 1.8</gadget>
<output>7.2</output>

<gadget id="calculator">2 * 2.5</gadget>
<output>5</output>

<gadget id="calculator">7.2 + 5</gadget>
<output>12.2</output>

<result>12.2</result>