2x - 5y + 6 = Statement 1
2x - 5y = 12 - 6
2x - 5y = 6
$$\frac{2x}{2}=\ \frac{\left(6\ +\ 5y\right)}{2}$$
$$x\ =\ \frac{\left(6\ +\ 5y\right)}{2}$$
No sufficient information for the value of x and y. Hence statement 1 is not sufficient.

Statement 2 = 8x - (4x + 10y) + 27 = 39
8x - 4x - 10y = 12
$$\frac{4x}{2\ }\ -\ \frac{10y}{2\ }=\ \frac{12}{2}$$
2x - 5y = 6
It is the same thing with statement 1 and it is not sufficient because the information for x and y is not enough.
Combining statement 1 and 2 together.
Statement 1 = 2x - 5y = 6
$$Statement\ 2\ =\ \frac{4x}{2\ }-\ \frac{10y}{2}\ =\ \frac{12}{2}$$
= 2x - 5y = 6
The two statement are equivalent to each other and since each statement alone is not sufficient, both statement combined are also NOT SUFFICIENT.
Option E is correct.