There are two chicken farms. Chicken farm A has (2/5) roosters and the rest are hens. The total number of chickens is 150 more than that of B chicken farm. All chicken farms in B are roosters. There are a total of 690 roosters in the field. How many hens does A chicken farm raise?
有两个养鸡场，甲鸡场有(2/5)是公鸡，其余都是母鸡，总只数比乙养鸡场多150只，乙养鸡场的全部是公鸡，两个养鸡场中的公鸡只数共690只．甲养鸡场养母鸡多少只？
<gadget id="calculator">690 + 150</gadget>
<output>840</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">840 / (7/5)</gadget>
<output>600</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">600 * (3/5)</gadget>
<output>360</output>

<result>360</result>