a) a + b = 2929
a : b = 103, rest 17
a = 103b + 17
103b + 17 + b = 2929
104b = 2929 - 17
104b = 2912
b = 2912 : 104 = 28
a = 103 x 28 + 17 = 2901
b) a - b = 794
a : b = 4, rest 83
a = 4b + 83
4b + 83 - b = 794
3b = 794 - 83
3b = 711
b = 711 : 3 = 237
a = 4b + 83 = 4 x 237 + 83 = 1031