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