SQL & PL/SQL

Hi:

There are three tables,

*1.TbReg*
reg_no,reg_name

Data:
RO1 Reg1
RO2 Reg2
RO3 Reg3

*2.TbZbr*
br_no,reg_no

Data:
092 RO1
013 RO1
020 RO3


*3.TbLM_Mast*
LM_no,br_no

Data:

1 013
2 013
3 020

Required O/p:

Reg_name | NoOfLeads |

RO1 | 2 |
RO2 | 0 |
RO3 | 1 |

From Above tables i want to write query for,

select total number of leads available in TbLM_Mast against each branch(*br_no*) from TbZbr,
and compare same reg_no with TbReg table and display required O/p/


So, how to write this query...?

Can any body help me...

Thank You,
Anup Desai