Then: A+B=28, B+C=25, A+C=23.
A+B+A+C=28+23
2A+B+C=5 1
2A+25=5 1
A=(5 1-25)/2= 13
13+C=23
C= 10
B+ 10=25
B= 15
Solution: A= 13, B= 15, C= 10.