The Set notation for A and B can be further clarified for a better understanding as follows:

A = { x: x is any rational number with 3 decimal points, 2 decimal points, 1 decimal point or no decimal point}

B= { x: x is any rational number with 2 decimal points only}

It is evident from the above definition of Sets A and B that elements of Set A with 3 decimal points, 1 decimal point or no decimal point, cannot be the elements of Set B

Hence SetA cannot be a subset of Set B