Răspuns :
Salut!
Răspuns: - 30 ✅
✏ 2 x [ 12 x 10 : 6 - ( 200 - 5 x 4 ) : 9 + 15 x 4 - a ] = 60
2 x [ 120 : 6 - ( 200 - 20 ) : 9 + 60 - a ] = 60
2 x ( 20 - 180 : 9 + 60 - a ) = 60
2 x ( 20 - 20 + 60 - a ) = 60
2 x ( 0 + 60 - a ) = 60
2 x ( 60 - a ) = 60
60 - a = 60 : 2
60 - a = 30
a = 30 - 60
a = -30 ✅