wdv is 83,815 rate of depreciation is 24 & no. of day is 75 how to calculate the depreciation

It depends upon Whether 

We are preparing

Depreciation as per Companies Act (Applicable for Companies)

or

Depreciation as per Income Tax Act (Applicable for Non Companies)

Dep as per Companies Act

We calculate Depreciation on the basis of number of days used as shown below

Dep as per Income Tax Act

We calculate Half Depreciation as asset used less than 180 days as shown below

Learn more

http://www.teachoo.com/840/259/Depreciation-Comparison-Companies-and-Non-Companies/Depreciation-Computation/author/teachoo

http://www.teachoo.com/214/65/Depreciation-Method/Depreciation-Computation-as-per-Income-Tax/author/teachoo