A+C =4
B+C =4.6
Add the three formulas to get: 2 (A+B+C) =7.5+4+4.6.
A+B+C =8.05
Subtract the above three formulas respectively to obtain:
A =8.05-4.6=3.45
B =8.05-4=4.05
C =8.05-7.5=0.55