(2) According to the meaning of the question: x+x+2+x+8+x+ 10=200,
Solution: x=45,
These four numbers are 45, 47, 53 and 55 in turn.
A: These four numbers are 45, 47, 53 and 55 in turn.
(3) it does not exist.
∫4x+20 = 420,
Solution: x= 100,
It's even, it doesn't matter, so it doesn't exist.