Răspuns:
(6+8+x):6=21
14+x=126
x=126-14=112
( 54 : 9 + 24 : 3 + x ) : 6 = 21
( 6 + 8 + x ) : 6 = 21
( 14 + x ) : 6 = 21
14 + x = 21 × 6
14 + x = 126
x = 126 - 14
x = 112
