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Here there is no symbol between 7 and 21.
7 + 21 = 28
21 + 9 + 7 = 37
5 + 2 + 3 + 7 + (21/7) = 20
21
7 + 7 + 7 = 21
13 + 21 - 7 + 12 = 15
7 + 21 + 2 + 86 + 4 = 120
It's 21.
7 + 5 + 4 ÷ 2 + 7 = 21
21
It is: 12+7+2 = 21
2 + 12 + 7 = 21
Are you trying to say 17 + 6 + (7-9) ? = 21