Problema Solution

David has $18 in his coin bank, he saved his money in $1 coins and $2 notes, there is a total of 14 coins and notes, how many $1 coins and $2 notes does he have in the coin bank?

Answer provided by our tutors

let


x = the number of $1 coins


y = the number of $2 notes


David has $18 in his coin bank:


x + 2y = 18


there is a total of 14 coins and notes:


x + y = 14


by solving the system of equations:


x + 2y = 18


x + y = 14


we find:


x = 10


y = 4


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David has 10 one dollar coins and 4 two dollars notes.