Răspuns :
( x + 20 ) : 12 + 68 = 78
( x + 20 ) : 12 = 78 - 68
( x + 20 ) : 12 = 10
( x + 20 ) = 10 × 12
( x + 20 ) = 120
x = 120 - 20
x = 100
( x + 20 ) : 12 = 78 - 68
( x + 20 ) : 12 = 10
( x + 20 ) = 10 × 12
( x + 20 ) = 120
x = 120 - 20
x = 100