A jar contains n nickels and d dimes. There are 20 coins in the jar, and the total value of the coins is 1.40. How many nickels and dimes are in the jar

Question

which is x and which is y.

Answer 1

20coins=dimes+nickles

$.1dimes+$.05nickles=$1.40

solve for dimes and nickles

20=x+y

$.1x+$.05y=$1.40

x=8

y=12

8 dimes and 12 nickles => .8 +.6=1.4

Answer 2

It shouldn't matter which is set up as x and which is y, as long as you are consistent with using them for the two equations you will need.

n + d = 20

n(.05) + d(.10) = 1.40

can become:

x + y = 20

x(.05) + y(.10) = 1.40

where x is now the number of nickels and y is the number of dimes.