Micheal and Adam can do together a piece of work in 20 days

Micheal and Adam can do together a piece of work in 20 days. After they have worked together for 12 days Micheal stops and Adam completes the remaining work in 10 days. In how many days Micheal complete the work separately.

80 days
100 days
120 days
110 days
90 days

Ans : 100 days