At the top or at the leak of his career?
Sorry. At the peak* My text book only lets me use one of these words. I thought both were right.
Could you throw some light into it.?

Thanks

Question

At the top or at the leak of his career?
Sorry. At the peak* My text book only lets me use one of these words. I thought both were right. 
Could you throw some light into it.?

Thanks

Answer

We usually talk of careers of having peaks and valleys.

There are several ways of using top, though, with slightly different meanings.
He’s on top. (He’s ahead of the others)
He’s on top of the world. (His life is going great in every respect)
He’s at the top of his game. (He’s playing the best he could have ever hoped to play.)