Ccalculate yearly straight line rate for 10 years

OK, here's a guess - you're asking about calculting straight-line depreciation, right? Just divide the cost of the capital expense item by 10, and that's how much you write off each year as depreciation expense, for 10 years.

That might depend if it's being done a proper accounting way, which could include a salvage (residual, tradein) value. If so, you have to subtract that off first.