Circular Formula & Reverse calculation

Hi,

I am working on the CTC structure changes for India. While computing for the restriction due to Minimum Wages, I have the below challenge.

Sample case:
Total CTC agreed is Rs. 75000/- out of which Statutory bonus will be Rs 3500/-. Remaining amount under CTC is Rs. 71500/-. Since CTC will comprise the Employer contribution in PF & ESI apart from Basic, reverse computation of Basic is mandated. Employer contribution in PF will be 12% & in ESI will be 4.75%. Need to arrive the basic so that the total CTC incl bonus is 75000.

It would be better if excel formulae is used for this calculation instead of Macro.

Please help.

Regards

S Rajesh