Riddle: David is throwing Robert a surprise birthday party but he has to stay within his budget. He spent half of his money plus $2.00 on the cake. Half of what he had left plus $2.00 was spent on balloons and streamers. Then he spent half of what he had left plus $1.00 on candy. Now he is out of money, how much did he start with?
Answer: This one is best solved working backwards, the last part David spent half of what was left plus $1.00 on candy and then was out of money. That means he must have spent $2.00 on Candy as $1.00 was half of what he had using the same logic backwards:
$2.00 on candy
$6.00 on Balloons and Streamers
$12.00 on the cake