1) To solve the first equation, we first need to simplify the expression on the left side:
3(4-x) = 12
34 - 3*x = 12
12 - 3x = 12

Now, we can isolate the variable x:
-3x = 0
x = 0

Therefore, the solution to the equation 3*(4-x) = 12 is x = 0.

2) To solve the second equation, we first need to simplify the expression on the left side:
42/(6-x) = 21
42 = 21*(6-x)
42 = 126 - 21x

Now, we can isolate the variable x:
-21x = -84
x = 4

Therefore, the solution to the equation 42/(6-x) = 21 is x = 4.