The magnification would be halved, resulting in 50x.
The total magnification of a microscope is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens. If the objective lens provides a certain magnification, and you change the ocular lens, the total magnification will be affected.
Each objective lens has its own magnification, and the overall magnification of the microscope is achieved by multiplying the magnification of the objective by the magnification of the ocular.
For example, if you're using a 10x objective and 10x oculars, the overall magnification would be 100x (10x objective x 10x oculars = 100x). But if you switched to 5x oculars, the magnification would be halved, resulting in 50x (10x objective x 5x oculars = 50x).