a bag contains 57 coins, with a total weight of 396 grams. if the bag contains only gold coins that weigh 8 grams each and silver coins that weigh 5 grams each, how many gold and how many silver coins are in the bag

Question

anonymous · Answer

let x-number of gold coins
y-number of silver coins

analyzing the problem you'll get two equations:
8x+5y=396-------> by the weight of the coins
x+y=57-----> number of coins in the bag

you're looking for y which is the number of silver coins in the bag.
solve it using elimination.