The average of 7 numbers is 28. If these 7 numbers are arranged in a row, the average of the first four numbers is 26, and the average of the last four numbers is 33. What is the fourth number?
7个数的平均数是28，把这7个数排成一列，则前四个数的平均数为26，后四个数的平均数为33，则第四个数是多少．
<gadget id="calculator">26 * 4</gadget>
<output>104</output>

<gadget id="calculator">33 * 4</gadget>
<output>132</output>

<gadget id="calculator">104 + 132</gadget>
<output>236</output>

<gadget id="calculator">28 * 7</gadget>
<output>196</output>

<gadget id="calculator">236 - 196</gadget>
<output>40</output>

<result>40</result>