What does the hypotenuse of a right triangle have to do with the legs??? PLEASE HELP!!!?

Like, if the hypotenuse is 25 meters, and one of the legs is 10 meters less than twice the other, how would you find the lengths of the legs? I'm in ninth grade, and in Algebra 2, so don't do anything, like, College Algebra or Trigonometry complicated.... Thanksssss!!!! :) <3