Alternate Method: Test the answer choices.
Total: $4.00 = 400 cents
Number of Coins: 35
Types of coins:
Nickels - 5 cents
Dimes - 10 cents
Quarters - 25 cents
Number of quarters is half the number of nickels.
Number of Quarters Choices: 3, 5, 6, 10, 20
Execution:20 Quarters = 20 x 25 = 500 cents. Too big. Eliminate 20.
For every 1 quarter there are 2 nickels.
1 Quarter + 2 Nickels = 35 cents. An Odd Number x 35 Cents = A Number Ending in 5. Dimes = 10 Cents. No number ending in 5 can be combined with numbers ending in 10 to add up to 400. Eliminate all odd numbers of quarters: 3, 5.
Left with 6 and 10.
6 x 35 = 210. Need 19 dimes to get to 400. Already have 6 x 1 Quarter + 6 x 2 Nickels = 18 coins. 19 + 18 > 35.
The only possible number of quarters left is 10.
Confirm: Quarters and Nickels: 10 x 25 + 20 x 5 = 350
Need 50 more to get to 400.
Dimes: 5 x 10 = 50
10 + 20 + 5 = 35 Coins
The correct answer is (B).