I assume you want the numbers added together?
In which case, you simply total the numbers together.
8 + 20 + 18 + 21 = 67
If I've assumed wrongly, then more information is needed.
4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21
18/20 + 8/20 - 5/20 = 21/20 or 1 and 1/20
10 + 8 + 20 + 7 = 10 + 20 + 8 + 7 = 30 + 15 = 45
7/8 of 21 is 18 3/8
20 - 4*4/8 = 20 - 16/8 = 20 - 2 = 18
what is the mode of the following data 18, 17, 12, 14, 8, 21, 10, 11, 19, 20, 10, 5, 17, 12, 10, 20
4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21
18/20 + 8/20 - 5/20 = 21/20 or 1 and 1/20
10 + 8 + 20 + 7 = 10 + 20 + 8 + 7 = 30 + 15 = 45
7/8 of 21 is 18 3/8
20 - 4*4/8 = 20 - 16/8 = 20 - 2 = 18
18/8 = 22/8 which simplifies to 21/4
GCF(20, 18, 8) = 2.
8 with remainder 20.
The Least Common Multiple (LCM) for 20 8 18 is 360.
-7/-8 x -20/-21 = 5/6
12 numbers (including 21). The numbers are 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21.