Sorry guys, Im not brilliant with the math so I need know exactly how we get the result in this equation
0 = P(fold) * $4.5 + (1 – P(fold)) * -$1.20875
The result is: P(fold) = 0.21
I mean how is the exactly processing of it?
How we conduct the math?
Thank you very much in advance 
0 = P(fold) * $4.5 + (1 – P(fold)) * -$1.20875
0 = P(fold)*$4,5 -$1.20875 + P(fold)*1.20875
0 = P(fold)($4,5 + $1.20875) -$1.20875
P(fold)($4,5 + $1.20875) = $1.20875
P(fold) = $1.20875 / ($4,5 + $1.20875) = 0.21
Just get P(fold) on one side of the equation and everything else on other side. It is done step by step in the reply above. 
