Question 146108
Jack = 2* Jill
Jack - 2Jill = 0

(3/4)(Jack+10) = Jill+10

Jack+10 = (4/3)Jill + 40/3
Jack = (4/3)Jill +10/3
3Jack = 4Jill + 10
3Jack - 4Jill = 10

Then solve using substitution or elimination. See here --> http://www.1728.com/unknwn2.htm

Jack 10, Jill 5