hello,

the formula for your first problem could be

=SUM(INDEX(Data!$B:$B,MATCH(Summary!C3,Data!$A:$A,0)):INDEX(Data!$B:$B,MATCH(Summary!$C$4,Data!$A:$A,0)-1))

I don't quite see what you want to achieve with the second problem. None of the data matches what you have in your description. Please explain exactly which cells to sum.

Offsetting upwards from the row labelled M, the value of 38 is achieved at row labelled F, not E. Please explain.