x+x+1=803; b:2-5=300; 36:(611-c)=18.

36:(611-с)36/611-с=1836/611-с=18 , с ≠ 61136=18 (611-с)36=10998 - 18с18с = 10998 - 3618с = 10962с = 609, с ≠ 611с = 609