Х/25-7/25=13/25; 53/63-(22/63-х/63)=43/63
Х/25 - 7/25 = 13/25 х/25 = 13/25 + 7/25 х/25 = 20/25 х = 25*20/25 х = 20 53/63 - (22/63 - х/63) = 43/63 22/63 - х/63 = 53/63 - 43/63 22/63 - х/63 = 10/63 х/63 = 22/63 - 10/63 х/63 = 12/63 х = 63*12/63 х = 12