Question

a+b=70 ,b+c=50,c+d=30,(a+b)-(c+d)=(a+b+d):2

Answer 1

a+b=70 ,b+c=50,c+d=30
(a+b)-(c+d)=(a+b+d):2
70-30=(70+d):2
sau  (70+d):2=40
70+d=2x40
d=80-70
d=10
Din relatia c+d=30
c+10=30
c=30-10
c=20
in relatia b+c=50 il aflam pe b
b+20=50
b=50-20
b=30
in relatia a+b=70, il aflam pe a:
a+30=70
a=70-30
a=40