Răspuns :
(78-x)+34=2030-45
78-x=1985-34
-x=1951-78
x=-1873
proba
(78-(-1873))+34=1985
78+1873+34=1985
78-x=1985-34
-x=1951-78
x=-1873
proba
(78-(-1873))+34=1985
78+1873+34=1985
(78-x)+34=2030-45
(78-x+34=1985
78-x=1985-34
78-x=1961
x=1961+78
x=2039