I only need the equations, I can solve it.

A pile of 22 coins consists of nickels and dimes. The total value of the coins is 1.20. Find the number of each type of coin.

How can you solve it if you don't know the equations? : P Just kidding ...

n+d=22, so we can say that d=22-n

5n+10d=120, and using d found above in this equation gives you:

5n+10 (22-n) = 120

5n+220-10n=120

-5n=-100

n=20, and since d=22-n, d=2

So there are two dimes and twenty nickels ...

check ...

20 (5) + 2 (10) = 100+20=120 cents which is $1.20

n+d=22, 20+2=22, 22=22

You have a pile of 22 coins that includes nickels and dimes

Let n = nickels and d = dimes

total coins = nickels and dimes

n+d=22

The total value of the coins is $1.20

d=1.20-n

You would solve by system of equations.

n+d=22

d=1.20-n

I suggest using process of substitution