Need help to write one SQL Query

Hi All,  
I have two tables as follows:

Table: MST
========
Id             Strt        Cnt            Nm
---            ------        -----            -----------------------------------------
1              101         100           X
1              310           90           Y
1              450          260          X
2              951            50          A
2             1050          160          Y

Table: LOCATOR
=============

Id            Strt          Cnt
---          -------         ------
1            151             40
1            251            500
2            959            100



I want to select rows from Table MST based on the rows from table LOCATOR. The joning columns are self explained
 
 
Any one can help ?
 
 
 
Thanks