Table:
0
A
B
C
D
E
F
G
H
I
1
#
President
Date of birth
Date of inauguration
Age at inauguration
End of term
Length of retirement
Date of death
Lifespan
2
1
Nkrumrah, Kwame Kwame Nkrumah
1909-09-21 21 September 1909
1July1960
50-284 50years, 284days
24February1966
2,254 days
1972-04-27 27 April 1972
days (62years, 219days)
3
2
Ankrah, Joseph Joseph Ankrah
1915-08-18 18 August 1915
24February1966
50-190 50years, 190days
2April1969
8,638 days
1992-11-25 25 November 1992
days (77years, 99days)
4
3
Afrifa, Akwasi Akwasi Afrifa
1936-04-24 24 April 1936
2April1969
32-343 32years, 343days
7August1970
3,245 days
1979-06-26 26 June 1979
days (43years, 63days)
5
4
Ollennu, Nii Nii Ollennu
1906-00-00 1906
7August1970
64-000 ~64 years
31August1970
5,844 ~16 years
1986-00-00 1986
29,220 ~80 years
6
5
Akufo-Addo, Edward Edward Akufo-Addo
1906-06-26 26 June 1906
31August1970
64-066 64years, 66days
13January1972
2,742 days
1979-07-17 17 July 1979
days (73years, 21days)
7
6
Acheampong, Ignatius Ignatius Acheampong
1931-09-23 23 September 1931
13January1972
40-112 40years, 112days
5July1978
0,346 days
1979-06-16 16 June 1979
days (47years, 266days)
8
7
Akuffo, Fred Fred Akuffo
1937-03-21 21 March 1937
5July1978
41-106 41years, 106days
4June1979
0,022 days
1979-06-26 26 June 1979
days (42years, 97days)
9
8
Rawlings, Jerry Jerry Rawlings
1947-06-22 22 June 1947
4June1979
31-347 31years, 347days
24September1979
days
2014-02-1
days (66years, 224days)
10
9
Limann, Hilla Hilla Limann
1934-12-12 12 December 1934
24September1979
44-286 44years, 286days
31December1981
5,867 days
1998-01-23 23 January 1998
days (63years, 42days)
11
10
Rawlings, Jerry Jerry Rawlings
1947-06-22 22 June 1947
31December1981
34-192 34years, 192days
7January2001
days
2014-02-1
days (66years, 224days)
12
11
Kufuor, John John Kufuor
1938-12-08 8 December 1938
7January2001
62-030 62years, 30days
7January2009
0, days
2014-02-1
days (75years, 55days)
13
12
Mills, John John A. Mills
1944-07-21 21 July 1944
7January2009
64-170 64years, 170days
24July2012
0 days
2012-07-24 24 July 2012
days (68years, 3days)
14
13
Mahama, John John Mahama
58-11-29 29 November 1958
24July2012
53-238 53years, 238days
0,000 Incumbent
0,000 Incumbent
2014-02-1
days (55years, 64days)

Questions and formulas:
Question: what's the date of birth with end of term being 2april1969
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:I1,F1="2April1969"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:I14,F2:F14="2April1969"),3))
Level: medium
Question: who is the the president with date of inauguration being 4june1979
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:I1,D1="4June1979"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:I14,D2:D14="4June1979"),2))
Level: medium
Question:  how many president with date of inauguration being 4june1979
Formula: ROWS(UNIQUE(FILTER(B1, D1="4June1979")))
Formula2: ROWS(UNIQUE(FILTER(B2:B14, D2:D14="4June1979")))
Level: medium
Question: what's the date of birth with end of term being 5july1978
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:I1,F1="5July1978"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:I14,F2:F14="5July1978"),3))
Level: medium
Question: what's the date of birth with # being 2
Formula: LET(query1,SUMMARIZE(C1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,2)=2))
Formula2: LET(query1,SUMMARIZE(C2:C14,SUMX(A2:A14)),FILTER(query1,CHOOSECOLS(query1,2)=2))
Level: hard
Question:  how many end of term with age at inauguration being 64-066 64years, 66days
Formula: ROWS(UNIQUE(FILTER(F1, E1="64-066 64years, 66days")))
Formula2: ROWS(UNIQUE(FILTER(F2:F14, E2:E14="64-066 64years, 66days")))
Level: medium