Given: a > b
From statement I: (86 * 42 + a)/(16-2b * 24a) = 643(2a  -  4)
218 * 22(2 + a) * 28b * 2-4a = 218(2a  -  4)
Then, 18 + 2(2 + a) + 8b  -  4a = 18(2a  -  4)
18 + 4 + 2a + 8b  -  4a = 36a  -  72
19a  -  4b = 47
From statement II: Difference between a and b is 2 and, 2(a + 3b  -  9) + 4a = 6(b  -  3 + a).
a = 2 + b
And, 2(a + 3b  -  9) + 4a = 6(b  -  3 + a)
2a + 6b  -  18 + 4a = 6b  -  18 + 6a
So, this equation is invalid as both sides are equal and also the value becomes zero.
From statement I and II:
19(2 + b)  -  4b = 47
38 + 19b  -  4b = 47
b = 3/5
Then, a = 2 + 3/5 = 13/5
Hence, both statements I and II together are sufficient.