expression, godan verb (-ru)
rack one's brain; think hard
Idiomatic expression for straining one's mind to come up with an idea or solution.
いいアイデアが浮かばなくて、みんなで知恵を絞った。
No good ideas came to mind, so we all racked our brains together.
彼は難問を解くために知恵を
He is racking his brain to solve the difficult problem.