Two white socks cost 25 cents more than a single brown sock. If two white socks cost 45 cents, how much would you pay for 15 brown socks? Let's think first. Chain of thought:
Two white socks cost 25 cents more than a single brown sock, meaning a brown sock is sold at $0.45 - $0.25 = $0.20. The cost of buying 15 brown socks is 15 * $0.20 = $3.
Therefore, the answer is 3.