There are 30 coins.All of them are dimes and nickels.They make $2.60.How many nickels are there? ...Show your steps.

Question

I have the answer but don't understand what steps to do.

Answer 1

Let the number of dimes and nickels be D and N. D+N=30 because there are 30 coins.

Their combined value is 10D+5N=260 (working in cents).

10(D+N)=10*30=300.

Subtract 10D+5N=260 and we get 5N=40 so N=8 (worth 40c). There are 8 nickels.

And D=30-8=22 (worth 220c). Combined value is 220+40=260c=$2.60.