I have a co-worker. This co-worker can't solve problems. He just lacks the ability completely. Give him an existing code base and an error, and he has NO IDE

I have a co-worker. This co-worker can't solve problems. He just lacks the ability completely. Give him an existing code base and an error, and he has NO IDEA how to proceed. Contrariwise, if he has to write something from scratch he can... as long as it's entirely stand alone and not too complex.