You have the right idea though. 15-20,000 fans at $2.10/ride would bring in $31,500-$42,000 and easily cover the $29K cost. If 35-40,000 fans go to a playoff game, can we guess that 1/2 of them ride metro ? If so, this should cover the costs.
Yes, Mathguy, I'm back in my "I haven't cracked a math book in 35 years" mode. It's just an order of magnitude.
