Question

Dave bowers collects u.s gold coins. He has a collection of 47 coins. Some are $10 coins, and the rest are $20 coins. If the face value of the coins is $670, how many of each denomination does he have?

Answer 1

670=10(a)+20(b)

47=a+b

a is amount of $10 coins=27

b is amount of $20 coins=20