Hi how would I write a formula to calculate the following

cell b2 contains 0.02169 cell B3 contains 0.01590 cell D2 contains 5860 and
column G contains numbers from 1 to 20845

Units Rate 1 0.02169 (first 5,860 units) 5860 £127.10
Units Rate 2 0.01590 20845 14985 £238.26
Total
£365.36

It is to calculate my gas bill where the first 5860 units cost .02169 and
the rest cost .01590
I can work it out manually but how do I write a formula that will calculate
it in excell?

Thanks Ron