Cake
• This is exactly why multiple-choice questions should be left for TV shows, not for school tests.

• 5th grade arithmetic approach: there are two dimes per each nickel. Make it a "group", which is 25c, and keep adding up groups until you hit \$1 (or just divide 1 by .25). You get four groups, which makes 4 nickels.

8th grade approach: a standard system of two linear equations:

10x + 5y = 100, x = 2y => 20y + 5y = 100, x = 2y => y = 4, x = 8

I would not be able to do this simple math in a stressful and time-limited situation of a TV show, so arithmetic method or test/exclusion as Pathfinder did works better in this case.

• I thought briefly about the two linear equations; but I realized by the time I wrote them out and solved them - like you I need paper and a pencil to parse them out - I already had my answer by inspection.

I always say it is good to know more than just one way to skin a cat.

• I started with the fact that he could not have ten dimes or more, therefore any number greater than 5 had to be wrong.

Then I calculated B and it was correct.