This looks difficult at first, but think of it this way: add up all of your coins (5 x .05) + (3 x .10) + (2 x .25) is 1.05, so you are 30 cents over the 75 cents. So figure out ways that you can make 30 cents with the available coins, take those away from 1.05 and you have 75 cents.
Remember these are the coins that you are taking away from $1.05
So now we can figure the coin combinations to use:
There are 18 ways to make change for 75 cents with only quarters, dimes and nickels.
many ways 4 quarters and 3 nickels 4 quarters and a dime and a nickel 3 quarters 8 nickels 3 quarters and 4 dimes etc etc etc
Three: one using only nickels, one using only dimes and one using only quarters!
Two quarters Three nickels Three pennies
Eight ways.
None. If you "get 65 cents using only dimes nickels and quarters" you are not using any pennies!
There are 5 ways to make 30 cents using quarters, nickels, and dimes.
There are 18 ways to make change for 75 cents with only quarters, dimes and nickels.
13
many ways 4 quarters and 3 nickels 4 quarters and a dime and a nickel 3 quarters 8 nickels 3 quarters and 4 dimes etc etc etc
6 dimes, 5 dimes 2 nickels, 4 dimes 4 nickels, 3 dimes 6 nickels, 2 dimes 8 nickels, 1 dime, 10 nickels, and 12 nickels.
Three: one using only nickels, one using only dimes and one using only quarters!
Two quarters Three nickels Three pennies
Eight ways.
19
Five different ways.
50 different ways