A pile of 55 coins, consisting of nickels and dimes, is worth $3.90. Find the number of each.

Solution:

Given, a pile has 55 coins consisting of nickels and dimes.

Let x be the number of nickels 

y be the number of dimes.

We have to find the number of each coin.

x + y = 55 ---------------- (1)

We know nickel is a five-cent coin.

Dime is a ten-cent coin.

So, 0.05x + 0.10y = 3.90 --------- (2)

Solving for x from (1) and (2)

From (1) y = 55 - x

Substitute y in (2)

0.05x + 0.10(55 - x) = 3.90

0.05x + 5.5 - 0.10x = 3.90

-0.05x = 3.90 - 5.5

-0.05x = -1.6

x = 1.6 / 0.05

x = 32

y = 55 - 32

y = 23

Therefore, a pile of 55 coins consists of 32 nickel and 23 dime coins.

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A pile of 55 coins, consisting of nickels and dimes, is worth $3.90. Find the number of each.

Summary:

A pile of 55 coins, consisting of nickels and dimes, is worth $3.90. The number of nickel and dime coins are 32 and 23.