Surely you did algebra at some point in your life. Substitute the definition of each into the third formula and solve.
c= .5a +1
b= .5c
a = .5b
1c= .125c +1
Solve.
.875c =1
c= 1.142857
b= .571
a= .2855
OOPS! c= .5a +1
b= .5c
a = .5b
1c= .125c +1
Solve.
.875c =1
c= 1.142857
b= .571
a= .2855
How can c be worth more than 1 BTC, when 1 BTC is all that is held in this incestuous relationship?
Spoiler: the answer is that there's only 50% of each company available to trade, hence their calculated sums being equal to 2