Table:
0
A
B
C
D
E
F
G
H
I
1
lesson id
customer id
lesson status code
staff id
vehicle id
lesson date
lesson time
price
lessons
2
1
6
Cancelled
8
3
2018-02-28 10:55:36
5
199.0
3
2
8
Cancelled
14
3
2018-03-07 16:12:36
6
167.0
4
3
6
Cancelled
11
2
2018-03-03 15:10:16
3
352.0
5
4
8
Completed
1
2
2018-03-17 19:02:07
9
306.0
6
5
10
Completed
3
2
2018-03-12 00:41:59
9
295.0
7
6
5
Completed
4
2
2018-03-07 22:03:49
6
492.0
8
7
9
Cancelled
11
1
2018-03-08 16:05:05
9
231.0
9
8
3
Completed
8
2
2018-03-21 06:48:45
2
277.0
10
9
2
Completed
4
2
2018-03-05 20:05:33
9
456.0
11
10
2
Cancelled
5
2
2018-02-26 02:36:35
4
495.0
12
11
10
Cancelled
15
1
2018-03-04 06:55:46
2
223.0
13
12
11
Cancelled
12
2
2018-03-16 07:08:52
2
184.0
14
13
13
Completed
12
1
2018-03-05 18:05:31
5
446.0
15
14
11
Cancelled
11
1
2018-03-07 11:53:32
5
483.0
16
15
3
Cancelled
8
1
2018-03-06 21:48:51
9
340.0

Questions and formulas:
Question: How many lessons were in cancelled state?
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium
Question: How many lessons have been cancelled?
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium
Question: total number of cancelled lessons 
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium
Question: the number of cancelled lessons 
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium
Question: total number of cancelled lessons 
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium
Question: the number of cancelled lessons
Formula: ROWS(UNIQUE(FILTER(I1, C1="cancelled")))
Formula2: ROWS(UNIQUE(FILTER(I2:I16, C2:C16="cancelled")))
Level: medium