Sami finds 3 spiders in the playground.  Hunter sees 12 ants climbing the wall.  Ming discovers 8 ladybugs in the sandbox, and watches 2 of them fly away. How many insects are remaining in the playground?
The children find 3 + 12 + 8 = <<3+12+8=23>>23 insects.
After the ladybugs fly away, there are 23 - 2 = <<23-2=21>>21 insects.
#### 21