1.X=2A

2.X=3B+ 1

3.X=5C+3

4.X=7D+3

Where a, b, c and d are all positive integers.

From 3.4, X+3 is a multiple of 5 and 7, so X+3 is a multiple of 35, and from 1, X is an even number, so X+3 is an even multiple of 35. Let X+3=35K, where k is an even number, then X=35K-3 is substituted into 2 to get 35k-3 = 3b+ 1.

So X=35K-3=35*5-3= 172.