Find the diminishing Musharakah is Following case.

Mr. Shakir requested Al-Barkah Islamic bank (AIB) for house financing on Diminishing Musharakah basis. AIB accepted the request and agreed to finance. To create Shirkat-ul-milk, Islamic bank and Shakir jointly bought a plot worth Rs. 10 mill in which Shakir's share was 30% and remaining was provided by Islamic bank. House construction, its renovation and others actual expenses were equal to Rs. 20.5 mill. Islamic bank financed 60% while remaining was provided by Shakir. After that Islamic bank gives its share in the house to Shakir on rent through lease contract. Rent of Islamic banks share in house was decided Rs. 80,000 / month [post paid rent]. In contract it was decided through a unilateral promise that Shakir will start to purchase Islamic bank's share from 3rd month of lease contract and he will buy each share at the beginning of each month. In the start of 3rd month of lease contract, market value of the house was estimated Rs. 40 mill. Shakir will buy Islamic bank's share in 20 equal installment.