First, let's solve the first equation:

(9x - 15) / 42 = 5
9x - 15 = 210
9x = 225
x = 25

Now, substitute x = 25 into the second equation:

(39 - 11x) 207 = 1242
(39 - 11(25)) 207 = 1242
(39 - 275) 207 = 1242
(-236) 207 = 1242
-48852 = 1242

Therefore, there seems to be a mistake in the second equation. Let's try to correct it.

If we distribute the 207 and solve:

(39 - 11x) 207 = 1242
8073 - 20711x = 1242
8073 - 2277x = 1242
-2277x = -6831
x = 3

Therefore, the correct solution is x = 3.