If the average of a and b is 7, what is the average of a+1 and b+3
如果a与b的平均数是7，那么a+1与b+3的平均数是多少
<gadget id="calculator">1 + 3</gadget>
<output>4</output>

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

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<result>9</result>