Răspuns :
1128 - b + 54 = 813
1128 - b = 813 - 54
1128 - b = 759
b = 1128 - 759
b = 369.
1128 - b = 813 - 54
1128 - b = 759
b = 1128 - 759
b = 369.
1128-b+54=813
1128-b=813-54
1128-b=759
1128-759=b
369=b