Twelve relatives always give gifts to one another. They have been doing it for eight years. How many exchanges have happened so far?

660 exchanges

Step-by-step explanation:

Number of relatives = 12

Number of years = 5

Since each relative gives gift to one another each year:

Then each relative hands out 11 gifts (person giving out the gift will not be counted) to the others, and others also do the same.

Therefore, yearly exchange :

(Number of relatives * number of gifts given out per person)

(12 × 11) = 132

Number of exchanges after 5 years :

(Number of yearly exchanges × number of years)

(132 × 5) = 660

the answer

b. they are parallel and will never intersect.