calculați a+b+c stiind ca: a=b+15, b=c-24, 67=c+38

Răspuns :

67=c+38
c=67-38=29
c=29

b=c-24 
b=29-24=5
b=5

a=b+15
a=5+15
a=20
_________________
a+b+c=29+5+20
a+b+c=54
67=c+38
c=67-38
c=29

b=c-24
b=29-24
b=5

a=b+15
a=5+15
a=20

a+b+c=20+5+29=54