Is it fat or muscle???

So recently I've been working out alot. Running a mile twice a week at school and other days just working out doing stations and excersises. I fence about 9 hours a week, and all that. But I've been really busy and haven't gone since school ended (around June). I have alot of leg muscles from pervious fencing and now athletics and i do have some abs under some flab, so no six packs or any definition. And i'm % foot 1 1/2 inches, and before school started i weighed around 102-105 and now i'm at 110!! Does that mean i got fatter or is it muscle?! I think i gained somr fat, but not that much. How can I tell if its fat or muscle?