Table:
0
A
B
C
D
E
1
Seat
Series 1
Series 2
Series 3
Series 4
2
1
Ivan Pilný
Michael Rostock
Michael Rostock
Michael Rostock
3
2
Ondřej Bartoš
Ondřej Bartoš
Ivan Pilný
Margareta Křížová
4
3
Dana Bérová
Dana Bérová
Dana Bérová
Petra Rychnovská
5
4
Marta Nováková
Marta Nováková
Marta Nováková
John Vanhara
6
5
Tomio Okamura
Tomio Okamura
Tomio Okamura
Michal Hanus

Questions and formulas:
Question: What shows for series 4 when the seat shows 1?
Formula: LET(query1,SUMMARIZE(E1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,2)=1))
Formula2: LET(query1,SUMMARIZE(E2:E6,SUMX(A2:A6)),FILTER(query1,CHOOSECOLS(query1,2)=1))
Level: hard
Question: What is the seat number when Series 3 shows Dana Bérová?
Formula: SUMIFS(A1,D1,"dana bérová")
Formula2: SUMIFS(A2:A6,D2:D6,"dana bérová")
Level: easy