This is a very open ended question. You can do this several ways. You can do this healthy by gaining muscle mass and eating properly. Up you calerie intake and go on runs to help build stamana and get in shape. Go to the gym and lift weights. Just be certain when you do this you must eat properly and healthy of you will not be building proper muscle mass
anywhere from 105 to 120
105 pounds - 120 pounds
if you're smaller around 105 to 120 is a healthy weight
105/120 x 100 = 10,500/120 = 87.5
Well I would say 105-120
108
105 through 120 but it doesnt matter because it depends on height
105 divided by 120 , then multiplied by 100 equals 87.5 percent
It is: 105/120 = 7/8 simplified
120
135
A normal, healthy weight for a 13 year old averaged sized person should be in range from 105 pounds to 120 pounds.