Open Question: how much calorie should i take if i burn everday about 800 calories by working out to lose weight instantly ?

well i need to lose around 30-35 kgs to be fit and i need to do that quickly......currently my weight is 98kg and i'm 15 year old and i'm 5 feet 11 inches.......and can you also suggest me how to increase my would be a great favour for me.