20A + B MOD 29
= 29A + B - 9A MOD 29
= B - 9A MOD 29 = 19
即
B - 9A MOD 29 = 19
B + 2A MOD 29 = 4
二式减一式有
11A MOD 29 = 14
11A = 29K + 14
A = (29K + 14)/11 = 2K + 1 + (7K + 3)/11
P = 11P + 9 ,A = 319P + 275
此时解得B = 29Q + 5
A、B的通解形式即如:
A = 319P + 275 或 319P - 44
B = 29Q + 5
P、Q属于整数