Good Riddles

Question: can you make an equation by using only the no.-4,4,4,4 whose answer will be 20.

Question: What goes up white and comes down yellow?

Question: What's a plate when it has three spoons in it?

Question: A cat,mouse,and dog all had an instrument,the dog had a flute,the cat had a trombone and the mouse's instrument bugs the dog.What was the mouse's instrument?

Question: (1) What am I and (2) how do you spell it?