Table:
0
A
B
C
D
E
1
Year
Conference
City
Country
Local Host(s)
2
2006
LCC1
Berkeley, California
United States
Sai
3
2007
LCC2
Berkeley, California
United States
Sai and Alex Fink
4
2009
LCC3
Providence, Rhode Island
United States
David Durand
5
2011
LCC4
Groningen
Netherlands
Christophe Grandsire
6
2013
LCC5
Austin, Texas
United States
Alex Sands

Questions and formulas:
Question: What is the sum of year with the local host Sai?
Formula: SUMIFS(A1,E1,"sai")
Formula2: SUMIFS(A2:A6,E2:E6,"sai")
Level: easy
Question: Who are the local hosts for the United States in years earlier than 2007?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,(D1="united states")*(A1<2007)),5))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,(D2:D6="united states")*(A2:A6<2007)),5))
Level: medium
Question: Which city has a conference of LCC2 and a year earlier than 2009?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,(A1<2009)*(B1="lcc2")),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,(A2:A6<2009)*(B2:B6="lcc2")),3))
Level: medium