There are 789 chickens in the farm, 69 less than ducks. How many ducks are there? (First write the equivalent relational expression, and then use two methods to list the solution of X.)
养殖场有789只鸡，比鸭少69只，鸭有几只？(先写等量关系式，再用两种方法列X解．)
<gadget id="calculator">69 + 789</gadget>
<output>858</output>

<result>858</result>