Answer:
3
Explanation:
In Set A, the minimum is 4 and the maximum is 7 without X which would make the range 7 - 4 = 3 but we want the range to be 4, therefore X has to be 4 + 4 = 8. Unfortunately, this would then make the range of Set B 8 - 1 = 7 so X has to be the smallest number in Set A which would be 7 - 4 = 3.