...............................=7/13
1) 2 2/5 : 6 1/15=12/5 : 91/15=12/5 * 15/91=36/91
2) 36/91+1 1/7=36/91+1 13/91=1 49/91=1 7/13
3) 5 5/7 - 5 1/16=5 80/112 - 5 7/112=73/112
4) 1 39/73 * 73/112=112/73 * 73/112=1
5) 1 7/13 - 1=7/13
AOB = 180 - 20 = 160
ACB = AOB / 2 = 80
Тут получается 437 сантиметров