# SOLUTION: mary has 18 coins, some quarters and the rest dimes. the total value of all the coins is \$3.45. Find the number of each of coin.

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 Question 183228: mary has 18 coins, some quarters and the rest dimes. the total value of all the coins is \$3.45. Find the number of each of coin. Answer by stanbon(57282)   (Show Source): You can put this solution on YOUR website! mary has 18 coins, some quarters and the rest dimes. the total value of all the coins is \$3.45. Find the number of each of coin. ---------------------------------------------------- Equations: Quantity Equation: q + d = 18 Value Equation...:25q+10d=345 cents ---------------------------------------- Multiply thru the 1st equation by 25 to solve for "d": 25q + 25d = 25*18 25q + 10d = 345 ------------------------- Subtract the 2nd equation from the 1s to get: 15d = 25*18 - 345 d = 7 (# of dimes) --- Substitute into q + d = 18 to solve for "q": q + 7 = 18 q = 11 (# of quarters) ==================================== Cheers, Stan H.