Răspuns :
538 - x + 821 = 1798
538 + 821 - 1798 = x
1359 - 1798 = x
x = - 439
538-(439)+821=1798
538+439+821=1798
1798=1798
538 + 821 - 1798 = x
1359 - 1798 = x
x = - 439
538-(439)+821=1798
538+439+821=1798
1798=1798
538-x+821=1798
a+821=1798
a=1798-821
a=977
538-x=977
x=977-538
x=439
538+439+821=1798
a+821=1798
a=1798-821
a=977
538-x=977
x=977-538
x=439
538+439+821=1798