I mean, how many workouts roughly?

I'm currently training 4 times a week. (This is my sixth week) Two whole body workouts with just 2 sets of about 8 exercises along with two dedicated cardio days, rowing and cycling.

My next goal is to add a long ( 1 hour) walk once a week just to get a few more calories burned and do some exercise outdoors for a change.

I'm not ready to go into split workouts with multiple sets and reps, and I'll never be able to train like you young fit guys.

But I'd like to lose about 10 lbs of fat and replace with 10 lbs of muscle. If I was dedicated, trained regularly and ate well, what's a realistic timeframe for that?