question: Gretchen has 110 coins. There are 30 more gold coins than silver coins. How many gold coins does Gretchen have?
answer: Let x be the number of silver coins Gretchen has
  Gretchen has x+30 gold coins.
  x+x+30=110
  2*x=80
  x=<<40=40>>40
  Gretchen has 40+30=<<40+30=70>>70 gold coins
  #### 70