[tex]\bf{768 \div 8 - 378 \div 6 + b = 1120}[/tex]
[tex]\bf{96 - 63 + b = 1120}[/tex]
[tex]\bf{33 + b = 1120}[/tex]
[tex]\bf{b = 1120 - 33}[/tex]
[tex]\boxed{b = 1087}[/tex]
Verificare:
[tex]\bf{768 \div 8} - 378 \div 6 +1087 = [/tex]
[tex]\bf{96 - 63} + 1087 = [/tex]
[tex]\bf{33 + 1087 =\boxed{1120} }[/tex]