27.1 problem 766
27.2 problem 767
27.3 problem 768
27.4 problem 770
27.5 problem 771
27.6 problem 772
27.7 problem 773
27.8 problem 774
27.9 problem 775
27.10 problem 776
27.11 problem 777
27.12 problem 778
27.13 problem 779
27.14 problem 780
27.15 problem 781
27.16 problem 782
27.17 problem 783
27.18 problem 784
27.19 problem 785
27.20 problem 786
27.21 problem 787
27.22 problem 788
27.23 problem 789
27.24 problem 790
27.25 problem 791
27.26 problem 792
27.27 problem 793
27.28 problem 794
27.29 problem 795
27.30 problem 796
27.31 problem 797