To solve for x in the first equation, we must isolate the variable x.

40x - 6 = 9
40x = 9 + 6
40x = 15
x = 15/40
x = 3/8

Now let's solve for x in the second equation:

x + 2 = 42
x = 42 - 2
x = 40

Finally, let's solve for x in the third equation:

23 - x = 3
-x = 3 - 23
-x = -20
x = 20

So, the solutions for x are x = 3/8, x = 40, and x = 20.