math help asap

Question

Dave Bowers collects U.S. gold coins. He has a collection of 36 coins. Some are? $10 coins, and the rest are? $20 coins. If the face value of the coins is ?$550?, how many of each denomination does he? have?

 

10 coins____?

20 coins____?

Answer 1

let the ten dollar coins = x

 

the twenty dollar coins = 36 - x

 

10x + 20(36 - x) = 550

 

10x + 720 - 20x = 550

 

-10x + 720 = 550

 

-10x = -170

 

x = 17

 

There are 17 ten dollar coins and 36 -17 = 19 twenty dollar coins