să se afle nr.a,b,c,știind că a+b=3000,b+c=5000,iar a+c=4000.​

Răspuns:

a+b=3000

b+c=5000

a+c=4000

a+b+b+c+a+c=3000+5000+4000

2a+2b+2c=12000

2x(a+b+c)=12000

a+b+c=12000:2

a+b+c=6000

3000+c=6000

c=6000-3000

c=3000

b+3000=5000

b=5000-3000

b=2000

3000+a=4000

a=4000-3000

a=1000

Explicație pas cu pas:

Răspuns:

a+b=3000=》 a=3000-b

b+c=5000=》c=5000-b

a+c=4000 =》 3000-b+ 5000-b=4000=》 8000-2b=4000=》 2b =8000-4000=》 b=4000÷2=》 b =2000

a=3000-b =》 a=3000-2000=》 a=1000

c=5000-b=》 c=5000-2000 =》 c=3000