pth wrote...
....
But what if Pmt is 35000 for first 12 Nper,and 10000 for next 12 Nper?

What I know is to use what if analysis find the rate is 10.2923.

You're mixing effective and nominal interest rates. 10.2923% is the
nominal annual interest rate.

Is there another way to solve this question? like ohter functions or macros??

You could try IRR.

=IRR({-500000;35000;35000;35000;35000;35000;35000;35000;3 5000;35000;35000;35000;35000;
10000;10000;10000;10000;10000;10000;10000;10000;10 000;10000;10000;10000})*12

returns 0.102922349.