Xiaogang's father's monthly salary is three times that of his mother's monthly salary. Xiaogang's father spent 2,800 yuan from his salary to buy an air conditioner, which was exactly half of the sum of Xiaogang's parents' salary. How much is Xiaogang's father's monthly salary?
小刚爸爸的月工资是妈妈月工资的3倍，小刚爸爸从工资中花2800元买了一台空调，用去的钱正好是小刚爸妈工资总和的一半．小刚爸爸月工资是多少？
<gadget id="calculator">2_800 * 2</gadget>
<output>5_600</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">5_600 / 4</gadget>
<output>1_400</output>

<gadget id="calculator">1_400 * 3</gadget>
<output>4_200</output>

<result>4_200</result>