Răspuns :
a+b+c+d=210
b=50+a
c=a-5
d=a+85
inlocuim b,c,d
a+50+a+a-5+a+85=210
4a+130=210
4a-80
a=20
b=50+20=70
c=20-5=15
d=20+85=105
b=50+a
c=a-5
d=a+85
inlocuim b,c,d
a+50+a+a-5+a+85=210
4a+130=210
4a-80
a=20
b=50+20=70
c=20-5=15
d=20+85=105
a+b+c+d=210
b=a+50
c=a-5
d=a+85
a+a+50+a-5+a+85=210
4a+130=210
4a=210-130
4a=80
a=80:4
a=20
b=70
c=15
d=105