Quick Algebra

 If the break even rate is 50%, then what are the straight up betting odds?

Using Algebra, the equation for calculating the break even rate using an underdog moneyline (variable x in this equation) is

1/(x/100+1)

If you had +100 odds, then you would get 1/(1+1) which equals 1/2, which is 50%.  If you decide not to use those strange negative odds and say a guy is +50 (bet 100 to win 50), then you would get (1/1.5) which equals 66%. If a team is +50, which is a fancy way of saying -200, then they have to win 66% of the time in order to profit. What if we had the break even rate, and wanted to see what the moneyline was?

Think of the moneyline as a ratio. If it is greater than 1, the team is an underdog, and if it less than 1, the team is a favorite. Given a break even rate, let's get an equation for the ratio. 

BE=break even rate

r=ratio (moneyline)

BE=1/(r+1)

BE(r+1)=1

r+1=1/BE

r=1/BE-1

there we are. Let's see it in action.

BE=50% (or 0.5.

r=1/0.5-1=2-1=r=1. 

BE=66%

r=1/0.66-1=0.51

r=0.51

Bet 1 to win 0.51

I wrote this to figure it out for myself but if you ever want to quickly calculate gambling stuff then y ou could use this as well.