13 + 21 - 7 + 12 = 15
13 + 23 + 12 + 7 = 55
2 + 12 + 7 = 21
It is: 12+7+2 = 21
6 + 13 + 2 + 12 + 7 + 14 = 54
7/8 + 13/24 = (7*3)/(8*3) + 13/24 = 21/24 + 13/24 = 34/24 = 17/12 or 1 5/12
13/21 - 7/21 = 6/21 Sorry, DJ, 4 over 7 = 12/21 so answer is 5/21
13/13 + 12/14 = 13/7 or 16/7
It's impossible for that to happen. 6 plus 7 is 13, not 12.
25 + 16 - 13 - 21 = 7
83
90
1/3 + 2/7 = 7/21 + 6/21 = 13/21