Răspuns:
a + ( 202 × 4 - 234 × 2 ) = 902
a + ( 808 - 468 ) = 902
a + 340 = 902
a = 902 - 340
a = 562
( 101 × 5 - 212 × 2 ) + a = 100
( 505 - 424 ) + a = 100
81 + a = 100
a = 100 - 81
a = 19
a - ( 234 × 2 + 202 × 2) = 49
a - ( 468 + 404 ) = 49
a - 872 = 49
a = 49 + 872
a = 921
( 123 × 3 + 112 × 4 ) - a = 289
( 369 + 448 ) - a = 289
817 - a = 289
a = 817 - 289
a = 528
