Answer:
No, Johnny is not correct
A U B = {a,b,c,d,e,f,g,h}
Step-by-step explanation:
Johnny's answer does not have c and d, elements that are in A and B, so A U B must have all elements that belong to A or B.
The (U) represents the sum of elements between two sets. So If a set has three elements {@,#,$} and another set has 5 elements {%,^,&}, (U) equals the sum of these sets: {@,#,$,%,^,&}.
The same is true for the sets A and B.
A = {a, b, c, d}
B = {c, d, e, f, g, h}
A U B = {a,b,c,d,e,f,g,h}
Note: c, d are repeated, in A and B. It is not necessary to write them twice in the final answer.