aggrigate week values in month

Hello All,

I have two questions:

1)Let say i have one month and it contains 5 weeks.when i select 2nd week it should show 2+3+4+5 weeks total,when i select 3rd week it should show 3+4+5 and when i select last week it should show only last week like ssame for the other weeks 

2)I have one month and it contains 5 weeks, if you select any one of 5 weeks it should show that month total

I want to write MDX for above questions

Thanks In Advance

Kiran.