Table:
0
A
B
C
D
E
1
Expression
Y = 2008
Y = 2009
Y = 2010
Y = 2011
2
a = Y mod 4
a = 0
a = 1
a = 2
a = 3
3
b = Y mod 7
b = 6
b = 0
b = 1
b = 2
4
c = Y mod 19
c = 13
c = 14
c = 15
c = 16
5
d = (19c + 15) mod 30
d = 22
d = 11
d = 0
d = 19
6
e = (2a + 4b − d + 34) mod 7
e = 1
e = 4
e = 0
e = 1
7
month = floor ((d + e + 114) / 31)
4 (April)
4 (April)
3 (March)
4 (April)
8
day = ((d + e + 114) mod 31) + 1
14
6
22
11
9
Easter Day (Julian calendar)
14 April 2008
6 April 2009
22 March 2010
11 April 2011

Questions and formulas:
Question: What is the y = 2008 when y = 2011 is a = 3?
Formula: FILTER(B1,E1="a = 3")
Formula2: FILTER(B2:B9,E2:E9="a = 3")
Level: easy
Question: What is the y = 2011 when the expression is month = floor ((d + e + 114) / 31)?
Formula: FILTER(E1,A1="month = floor ((d + e + 114) / 31)")
Formula2: FILTER(E2:E9,A2:A9="month = floor ((d + e + 114) / 31)")
Level: easy
Question: What is the y = 2011 when the y = 2010  is 22 march 2010?
Formula: FILTER(E1,D1="22 March 2010")
Formula2: FILTER(E2:E9,D2:D9="22 March 2010")
Level: easy
Question: What is the y = 2011 when the y = 2009 is 6 april 2009?
Formula: FILTER(E1,C1="6 April 2009")
Formula2: FILTER(E2:E9,C2:C9="6 April 2009")
Level: easy
Question: what is the y = 2008 when the expression is easter day (julian calendar)?
Formula: FILTER(B1,A1="Easter Day (Julian calendar)")
Formula2: FILTER(B2:B9,A2:A9="Easter Day (Julian calendar)")
Level: easy
Question: what is  the y = 2009 when the expression is month = floor ((d + e + 114) / 31)?
Formula: FILTER(C1,A1="month = floor ((d + e + 114) / 31)")
Formula2: FILTER(C2:C9,A2:A9="month = floor ((d + e + 114) / 31)")
Level: easy