The equation that can be used to find the number of years it will take for the populations of the two animals to be equal is:
200 - 15n = 150 - 5n
To solve the equation, we can begin by simplifying it:
200 - 15n = 150 - 5n
-15n + 5n = 150 - 200
-10n = -50
n = (-50)/(-10)
n = 5
Therefore, it will take 5 years for the population of moose and mountain goats to be equal.