Answer:
Johnny is wrong.

Step-by-step explanation:
Johnny is wrong.
A better definition would be:
is the set of all elements that belong to at least one A or B.
So, the elements that belong to both A and B, like c and d in this exercise, also belong to
.
So:

This is really simple. She had 4/6 ft plus 5/6 ft ribbon. This is equal to 1.5 ribbon.