What song lyric does this rebus describe?

Caspar says "Idiots will always enter a burning building."
Melchior says "They will do so, even when no one else will try."
Balthasar says "Not only that, but those dupes will do it quickly."

Which word in Group B can be added to Group A? Why?

Group A: complex, on, rat, stall
Group B: accord, gallop, new, tandem

Letter Equations are well known phrases or facts where the key words have been replaced with the first letter of that word. These are often in the form of an equation, which contain a number, an = sign and the rest of the obscured phrase or fact.

10 = M per P in C C

You have four lengths of gold chain. One is made up of five links, two are made of four links, and one made of three links. These need to be made into one bracelet. The jeweler you have taken them to charges 50 cents to break a link and $1.00 to weld a link back together. You figure it would cost $6.00, but the jeweler finds a cheaper way. What is it and how much will it cost?