Answer:
The answer is 3 houses.
Explanation:
This question is based on the Least Common Multiple (LCM) method. We will find the LCM of the numbers 4, 6 and 8.
4 = 2 x 2 =

6 = 2 x 3 = 2 x 3
8 = 2 x 2 x 2 =

So, LCM is =

Therefore, at every 24th houses, we will find all three trolls colors.
And 24 is the number of houses we will find all color trolls. Then in a group of 75 houses, it will occur thrice and at every 24th place. Means. 3 houses will have all color trolls.