Complicated nested formula assistance (believe I can use "if" formula, not 100% sure)

Hi everyone,

Please see my problem below (file attached):

I believe I only need to write one formula and it can be applied to columns K-N. I was going to use customer number (as opposed to name) when I wrote the formula.

Here are the parameters:
- If invoice is over BRL 5,000.00 (column F) and customer is Americel, Claro, Nextel or Tim Cellular – then columns K-N should be billed amount (column F) multiplied by tax rate (amounts in row 3, columns K-N).
o Any invoice amount under BRL 5,000 (column F) for the above customers – then column K should be billed amount (column F) multiplied by tax rate (in row 3, column K) and columns L-N should be zero.
o However, if invoice tax amount is under BRL 10.00 (column G) for above customers – then columns K-N should be 0
- Customer Vivo should be zero for columns K-N.

Thanks in advance for your assistance,
Jessica