347 + (650 : y - 28) = 449

347 + (650:у -28) =449
650:у -28 = 449-347
650:у - 28 = 102
650:у = 102+28
650:у= 130
у= 650:130
у= 5

проверим:
347 + (650:5 -28) =449
347+ (130-28)=449
347 +102=449
449=449