zu entscheiden, was

to decide what

→ zu
phrase Rare #41,324
to decide what Used in an infinitive clause followed by a subordinate clause to express deciding what someone will do, choose, or determine. The verb in the subordinate clause usually comes at the end.
GE: Es liegt an dir, zu entscheiden, was du machst.
EN: It is up to you to decide what you do.

Es liegt an Ihnen, zu entscheiden, was Sie machen.

It’s up to you to decide what to do.

Es liegt an dir, zu entscheiden, was du machst.

It's up to you to decide what you do.

Ich bin an der Reihe, zu entscheiden, was wir essen.

It's my turn to decide what we eat.

Jetzt, da du erwachsen bist, ist es an dir zu entscheiden, was du tun willst.

Now that you're an adult, it's up to you to decide what you want to do.

Mario ist alt genug, um zu entscheiden, was er tun muss.

Mario is old enough to decide what he needs to do.

— Lohn der Angst (1953)