Mary has a collection of nickels and quarters for a total value of 4.90.if she has 42 coins total how many of each kind are there

Let x be the number of nickels and y be the number of quarters.

Then, x + y = 42 --- (1)

It is given that total value = 4.90.

Therefore, 0.05x + 0.25y = 4.9 --- (2)

Multiply (1) by 0.25

0.25x + 0.25y = 10.5 --- (3)

Now, subtract (2) from (3), we get,

0.2x = 5.6

Divide both sides by 0.2.

x = 28

x + y = 42

y = 42 - x

= 42 - 28

= 14

Hence, Mary has 28 nickels and 14 quarters in total.