I think that we have to consider the time obama arrived as t1, and the time hilary arrived as t2.
Eventually, we can get z as t1-t2
After that we can calculate this problem.
I hope this is right.
I think that we have to consider the time obama arrived as t1, and the time hilary arrived as t2.
Eventually, we can get z as t1-t2
After that we can calculate this problem.
I hope this is right.