The postman delivered 260 letters on the first day, 150 more on the second day, and 12 fewer on the third day. How many letters were delivered in three days?
邮递员第一天送了260封信，第二天比第一天多送150封，第三天比第二天少12封．三天一共送了多少封信？
<gadget id="calculator">260 + 150</gadget>
<output>410</output>

<gadget id="calculator">150 - 12</gadget>
<output>138</output>

<gadget id="calculator">260 + 138</gadget>
<output>398</output>

<gadget id="calculator">260 + 410 + 398</gadget>
<output>1_068</output>

<result>1_068</result>