Tiffanny has 100 coins in dimes and nickels. She has a total of $5.80. How many of each coin does she have. Write the equations then solve.

Answer 1

10d + 5(100-d) = 580
10d + 500 - 5d = 580
5d = 80
d = 16

so, 16 dimes: $1.60
84 nickels: $4.20

Answer 2

I'm doing systems of equations so can you do it
Like
X+y= 100. Y=-x+100
10x+5y=580. Y=-2x+116