arrayFormula

Hi there.

One of the possible solutions is:

1. On sheet Lookup, cell B2, put the following formula:

 

=COUNTIF('Data'!A2:A;A2)

 

and copy it down as far as you have data in column A.

 

2. On the same sheet, cell C2, put the following formula:

 

=sum(arrayFormula((Data!A1:A=A2)*(Data!B1:B="yes")))

 

and copy it down as far as you have data in column A.

 

Best regards,

Otávio