Usage of symbols, less than and larger than

Question

This is probably a stupid question, but I have to ask anyway since it's been bothering me since my lecturer said it. He said that $20\leq x \leq 35$ cannot be written as $35\geq x\geq 20$ since "$35$ can't be larger than $20$". I have been taught that those two are the same and I find his argumentation strange.
Can $20\leq x \leq 35$ be written as $35\geq x\geq 20$?

Answer 1

Your lecturer is wrong (assuming you have understood and reported his claim correctly). $a \le b$ is exactly equivalent to $b \ge a$, usually by definition. So "$20 \le x \le 35$" and "$35 \ge x \ge 20$" are equivalent.

Also, 35 is larger than 20, so I have no idea what that explanation is about.

Answer 2

Sure it can, the two chains are the same!

Answer 3

20≤x≤35 ___|_______________|______|________|________________|________
-35 -20 0 20 35

-35 is less than or equal to x is less than or equal to -20. -20 is greater than or equal to x is greater than or equal to -35

20 is less than or equal to x is less than or equal to 35. 35 is greater than or equal to x is greater than or equal to 20