If it is Thursday on the west side of the international date line what day is it on the east side

If it is Thursday on the west side of the International Date Line then moving of the east side would result in the Wednesday.

Explanation:

As we move from east side to the west side of the international date line then we will travel a day forward

i. e. Sunday on the east side has the Monday running in the west side of the international date line in an exact instant of time.

It is due to the rotation of the earth around the axis.