Essentially, because ABCDE and JKLMN are similar, their corresponding sides have a common ratio. To find x, we can simply the ratio between NJ and its corresponding side equal to the ratio of another pair of corresponding sides.
3x = 3.6
x = 1.2
T-T this took waaaaaay too long to be helpful but I hope it is anyways!
The answer is 1.2 each side on the bigger shape that correlated with that side on the smaller shape, can be scaled down by a certain amount to get a value for that particular side. So in this problem you would do 2/1.666666666666667 Wich equals 1.2