Joe has a collection of nickles and dimes that is worth $7.65.If the number of dimes was doubled and the number of nickles was increased by 35, the value of the coins would be $14.30. How many nickles and dimes does he have?

Answer 1

It's spelled nickels.

Let x = number of nickels (originally)
let y = number of dimes (originally)

5x + 10y = 765

5*(x + 35) + 10*(2y) = 1430
5x + 20y = 1430 - 175 = 1255

The x terms are easily eliminated
10 y = 490

y = 49
5x = 765 - 490 = 275
x = 55