Răspuns :
a+b+c=710
b=15+2a
c=3b-25
a+15+2a+3b-25=710
a+15+2a+3b=735
3a+3b=720
a+b=240
(a+b+c)-(a+b)=710-240
c=470
470=3b-25
495=3b
b=165
a=240-165
a=75
b=15+2a
c=3b-25
a+15+2a+3b-25=710
a+15+2a+3b=735
3a+3b=720
a+b=240
(a+b+c)-(a+b)=710-240
c=470
470=3b-25
495=3b
b=165
a=240-165
a=75