In the following number-pairs, the second number is obtained by applying certain mathematical operations to the first number. Which numbers should replace X and Y so that the pattern followed by the two numbers on the left side of:: is same as that on the right side of ::?
906 : X :: 391 : Y
1
X = 351 and Y = 245
2
X = 135 and Y = 223
3
X = 225 and Y = 169
4
X = 710 and Y = 250