Răspuns :
ab+ac=84
=> a x (b+c) =84
=> 7 x (b+c) =84
=> b+c = 12
3b+3c-30=
=3 x (b+c) -30
=3 x 12 - 30
=36-30=6
=> a x (b+c) =84
=> 7 x (b+c) =84
=> b+c = 12
3b+3c-30=
=3 x (b+c) -30
=3 x 12 - 30
=36-30=6