C. Algebra
posted by Leissa .
A stack of $10 bills is worth $90 billion dollars. What is the height of the stack in kilometers? Assume each bill is .2 millimeters high.

Number of bills = $10,000,000,000 / $10
= 1,000,000,000
each bill is 0.2mm = 0.0002m = 0.0000002km
Total thickness=1,000,000,000*0.0000002km
=?
(It's a little more than half the distance between New York City and Boston).