Conversation so far:
which college did Phil Mickelson play for?
Arizona State University.
who did he play with?
CANNOTANSWER.
what did he do after college?
his first PGA Tour event.
what did he win in college?
Over the course of his collegiate career, he won 16 tournaments.
what hand did he use ro play golf?
left-handed swing.

Question: what age was he during college?
Self-contained rewrite: what age was Michelson during college?