14. ......=(3 8/12+1 9/12):(6 7/12 - 2 3/12)*4/5=5 5/12 : 4 1/3 * 4/5=65/12 * 3/13 * 4/5=65/12 * 12/65=1
15. .......=(3 8/24 - 1 21/24) * 24+63/2 * 1/3=1 11/24 * 24+21/2=35+10 1/2=45 1/2
16. .......=(8 - 16/7 * 35/12) * 27/56+5/14=(8 - 20/3)*27/56+5/14=(8-6 2/3)*27/56+5/14=1 1/3 * 27/56+5/14=4/3 * 27/56+5/14=9/14+5/14=14/14=1
17. ......=(2 16/60 - 1 25/60) * 5/17+58/9 * 1/2=51/60 * 5/17+29/9=3/12+3 2/9=9/36+3 8/36=3 17/36
18. ........=(3 22/54 - 2 51/54)*27/50+18/5 * 1/3=25/54 * 27/50+1 1/5=1/4+1 1/5=5/20+1 4/20=1 9/20