Xavier has 51 coins in nickels and dimes and has 4.15 in all how many of each does he have

Start a basic equation

n = nickel

d = dimes

n + d = 51

since nickels are five cents, it is. 05

And since dimes are ten cents, it is. 10

So the second equation is. 05n +.10d = 4.15

If n + d = 51, than n = 51 - d

plug that into the second equation

.05 (51-d) +.10d = 4.15

Solve the equation

d = 32

Plug that into n = 51 - d (32) to get 19

32 dimes and 19 nickels