Question

A certain comet is visible on earth once in every x years - that is, it has a periodicity of exactly x years. Three of the years in which it was seen are 1780, 1861 and 1987. Which of these could be the value of x?
a) 2 b) 5 c) 6 d) 9
answer with solution if u want to be marked as brainliest​​

Answer 1

Answer:

9 is the value of x

1861 is answer