graph intersection

EDIT

Given: A = {2, 3, 4}; B = {1, 3, 5}; C = {5, 6, 7, 8} Find A U B

A U B  = {1, 2, 3, 4, 5 }

[ This is a "union"  rather than an intersection ]

Given: A = {2, 3, 4}; B = {1, 3, 5}; C = {5, 6, 7, 8} Find A U B

={2 U, 9 U, 20 U}

Evaluate A U B where A = {2, 3, 4}, B = {1, 3, 5} and C = {5, 6, 7, 8}:
A U B  =  {2, 3, 4} {1, 3, 5} U

(2, 3, 4) U (1, 3, 5) = U (2×1, 3×3, 4×5):
U (2, 3×3, 4×5)

3×3  =  9:
U (2, 9, 4×5)

4×5  =  20:
U (2, 9, 20)

U (2, 9, 20) = (U×2, U×9, U×20):
Answer: | 
| (2 U, 9 U, 20 U)