a) -3 x (3/12 + -6/7 + 8/21)
First, let's simplify the fractions inside the parentheses:
3/12 = 1/4
-6/7 remains the same
8/21 remains the same

Now, let's add the fractions inside the parentheses:
1/4 + -6/7 + 8/21 = (21/84) + (-48/84) + (32/84) = 5/84

Finally, let's multiply the result by -3:
-3 x 5/84 = -15/84 = -5/28

Therefore, the answer is -5/28.

b) -2/3 x ( 2/18 + -6/12 + -3/33)
First, let's simplify the fractions inside the parentheses:
2/18 = 1/9
-6/12 = -1/2
-3/33 = -1/11

Now, let's add the fractions inside the parentheses:
1/9 + -1/2 + -1/11 = (22/198) + (-99/198) + (-18/198) = -95/198

Finally, let's multiply the result by -2/3:
-2/3 x -95/198 = 190/594 = 95/297

Therefore, the answer is 95/297.

c) 6/-14 + 4/25 + 5/10 + -3/16
First, let's simplify the fractions:
6/-14 = -3/7
5/10 = 1/2
-3/16 remains the same

Now, let's add the fractions:
-3/7 + 4/25 + 1/2 + -3/16 = (-120/175) + (28/175) + (87/175) + (-33/175) = -38/175

Therefore, the answer is -38/175.

d) -4/9 x (1/26 - 32/64 + -4/32)
First, let's simplify the fractions inside the parentheses:
1/26 remains the same
32/64 = 1/2
-4/32 = -1/8

Now, let's subtract the fractions inside the parentheses:
1/26 - 1/2 + -1/8 = (8/208) - (104/208) + (-26/208) = -122/208

Finally, let's multiply the result by -4/9:
-4/9 x -122/208 = 488/1872 = 61/234

Therefore, the answer is 61/234.