Question

In a change jar, Tom has nickels and dimes. The number of nickels is two times the number of dimes and the total amount of money in the jar is $1.20. How many dimes are in the jar?

Answer 1

Nickels are worth .5 and dimes are worth .10. You could set up x as the number of nickelse and y as the number of dimes. So you could set up your first equation as:
.5x+.10y=1.20

Second equation: 2x=y now you could just plug in 2x for y in the first equation and solve your equation

Answer 2

number of dimes --- x
number of nickels --- 2x

10x + 5(2x) = 120
20x = 120
x = 6

So 6 dimes and 12 nickels