2 × { 12 + 3 × [ 60 - 3 ×( 27 - 12 )]} - 5x = 7
2 × { 12 + 3 × [ 60 - 3 × 15 ]} - 5x = 7
2 × { 12 + 3 × [ 60 - 45 ]} - 5x = 7
2 × { 12 + 3 × 15 } - 5x = 7
2 × { 12 + 45 } - 5x = 7
2 × 57 - 5x = 7
114 - 5x = 7
-5x = -114 + 7 imnultim toata ecuatia cu -1 pentru a fi 5x , nu -5x ⇒
5x = 114 - 7
5x = 107
x = 107 : 5
x = 107 supra 5