I want to calculate number of records(count row). What is the simplist way?

I have this Registration form with 2 subForms in one page.

[SubForm1]

Sub Total 1 = number of rows added on SubForm2 x 25000

[SubForm2]

Sub Total 2 = number of rows added on SubForm2 x 50000

Grant Total = Sub Total 1 + Sub Total 2

Pretty simple, isn't it?

But I can't get over with this for 12 hours now. Can someone help me?

I need to know where to put the script with what.