52 - ( 2660 : 76 + x ) : 23 = 28
52 - ( 35 + x ) : 23 = 28
( 35 + x ) : 23 = 52 - 28
( 35 + x ) : 23 = 24
35 + x = 24 × 23
35 + x = 552
x = 552 - 35
x = 517
verificare :
52 - ( 35 + 517 ) : 23 =
52 - 552 : 23 =
52 - 24 = 28
