[Fabian]

The way I think about it is this:

Every time you push instead of checkfold (assume 0% fold equity here), you lose $150. Every time you push and make him fold, you win $1000. To make up for the $150 losses, you need to make him fold 150 / (150+1000) = 13ish% of the time. Intuitively this makes sense to me, and the math checks out too of course. Also not sure what the question is exactly so maybe this reply was useless.