Răspuns:
647 × 4 - a = 1728
2588 - a = 1728
a = 2588 - 1728
a = 860
9000 - 375 × 15 + b = 7134
9000 - 5625 + b = 7134
3375 + b = 7134
b = 7134 - 3375
b = 3759
c-( 85 : 5 × 172 ) = 3985
c - ( 17 × 172 ) = 3985
c - 2924 = 3985
c = 3985 + 2924
c = 6 909