Question

Se da a+b= 19 , b+c =21 si a+c=20.
Calculti a+b+c si determinati numerele a,b,c

Answer 1

a+b+b+c+a+c=
19+21+20= 60

2a+2b+2c=60

a+b+c=60:2
a+b+c=30

19+c=30
c=30-19
c=11

b+11=21
b=21-11
b=10

a+11=20
a=20-11
a=9