Table:
0
A
B
C
D
E
1
Office
Type
Location
Took Office
Left Office
2
State Representative
Legislature
Dover
January 6, 1801
January 5, 1802
3
State Representative
Legislature
Dover
January 5, 1802
January 4, 1803
4
State Representative
Legislature
Dover
January 4, 1803
January 3, 1804
5
State Attorney General
Executive
Dover
1806
1810
6
U.S. Senator
Legislature
Washington
January 12, 1810
March 3, 1815
7
U.S. Senator
Legislature
Washington
March 4, 1815
March 3, 1821

Questions and formulas:
Question: What date did the executive office in Dover take office?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,(C1="dover")*(B1="executive")),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,(C2:C7="dover")*(B2:B7="executive")),4))
Level: medium
Question: What left office date happened in Washington?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="washington"),5))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,C2:C7="washington"),5))
Level: medium
Question: What type of office left office in 1810?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,E1=1810),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,E2:E7=1810),1))
Level: medium