设甲数为a 乙数为b 甲乙两数的差是1902 a-b = 1902 a = b+1902 甲数除以乙数的商20,余数是21 (a-21)/b = 20 a = 20b + 21 b+1902 = 20b+21 19b = 1881 b = 99 a= 2001 甲数=2001 乙数=99
