How much cardio should I do to lose 1% of body fat every week?

I'm a male, 18 years old, and weigh 155 lbs. My body fat percentage right now is about 14 percent. I did some calculations and I think i would have to lose 1.5 lbs of fat to lose 1% of body fat. Is this accurate? I also don't want to lose that much muscle... When doing cardio you lose more fat than muscle but what's the ratio? It's like 1:4 right? I want to get abs without going below 150 lbs and losing that much muscle. When I flex the top 4 abs are quite visible along with 2 obliques on each side. However, I want my abs to be visible without me flexing. Only my two upper abs are visible when i'm not flexing. What do I have to do? How much cardio? I don't have much endurance (i got mitral valve prolapse)... I can run a mile like in 9 minutes. Oh i lift weights 5 days a week. So yea?? Oh and do you think is possible that i can get abs within two months?