Your ideal body weight should be 60 kgs. Keep a target of two to three kgs weight loss per month and don't give up in between till you reach your target.
With exercises if you follow diet than only you lose weight.
On diet, you should follow100% or weight loss becomes difficult. At your age falling for temptation is very easy, so please first promise yourself that you will dedicate yourself 100%.
For your age I will not advise restrictive diet as your is growing age....rather I will advise you three home made meals with salads, dal, pulses, buttermilk. Please totally avoid sweets, sugar ,fried,chocolates,bakery products, junk foods, ice creams, chats and hotel food.
Gift yourself some tasty food after three kgs weight loss.