Crafts

It would be an easy repair, and if I understood what you so carefully wrote, not terribly noticeable.
(I'm assuming you don't sew, so please don't be insulted by my directions.) You want to make a seam of the tear. That means you want to sew on what we call the "wrong" side of the fabric (which is the fabric of the inside of the pant leg.)
So turn the pant leg inside out. Match up the two ragged edges of the tear (which in sewing means you will be putting the two "right" (=outside) sides of the fabric together. Thread a needle (I assume you don't have a sewing machine) and knot the ends (so what you're sewing with is a double thread.) As long as you have even a 1/4" seam you'll be fine. Use stitches as small as you can manage. At the hem edge, reinforce the very end of the seam to keep it from ripping again.

I'm sure you'll be victorious!