13 plus 13 is equal to 26
1/6 + 7/10 = 5/30 + 21/30 = 26/30 = 13/15
-30 plus 60 = 30
13 plus 13 would equal 26.
30*13 = 390
30 + 80 = 110
half of 30 is 15, so 15 added to 15 would equal 30. if you go from there and add one number and subtract one number from each 15 (14 plus 16, 13 plus 17, ect...all the way to 0 plus 30) these numbers will also total to 30.
-13
27+24+13 = 64
2+40+30=72
30 + 50 + 70 = 150
13 + 5 = 18