I have a problem I can't solve as below.

If someone wanted to be paid a nett figure of £912.00 but has a 10% subcontractor allowance deducted but they themselves have a 4.5% surcharge what is the original figure that I would need to pay them? I really need to know a formula to get to this original figure. See example below;

Nett Figure = £912.00

Therefore we pay £969.70 (Derived from guess work). This is the figure I need to know

Less 10% (£96.97) = £872.73

Plus 4.5% (39.27) = £912.00 Nett

Thanks.