The fruit supermarket shipped 1200 kilograms of oranges. After selling (2/5), the remaining oranges are equal to 40% of the mass of the apples. How many kilograms are the original apples?
水果超市运来了桔子1200千克，卖出(2/5)后，剩下的桔子与运来的苹果质量的40%相等．原来苹果多少千克？
<result>1_800</result>