can't "easily" lose 10lb a month, with diet and good exercise 3-5 times a week, maybe.
I've been on a weight loss journey since i quit RS and have dropped around 25-30lb since july, losing 1-2lb/week, with exercise(sometimes p90x) and 1000-1500 cals/day
Bare in mind that 1lb of fat equates to 3500 calories, you have to burn 3500 calories to lose 1lb of fat. so if you deficit your calories by 500/day you'll lose 1lb a week, 1000/day and 2lb a week, 1250 cals a day for 2.5lb/week or 10lb a month would be pretty tough.