1) 3 \frac{1}{8} +7 \frac{5}{12} +5 \frac{3}{8} + \frac{1}{12} = 3 \frac{1}{8} + 5 \frac{3}{8}+7 \frac{5}{12} + \frac{1}{12}= 8 \frac{4}{8} +7 \frac{6}{12}= 8 \frac{1}{2} +7 \frac{1}{2}= 15 \frac{2}{2} = 16
2) 10 \frac{2}{5} + 3 \frac{3}{5} +15 \frac{5}{6}+4 \frac{1}{6}= 13 \frac{5}{5} + 19 \frac{6}{6}= 14+20=34
3)9 \frac{7}{8} +1 \frac{1}{8} + 5 \frac{2}{7} +4 \frac{5}{7} = 10 \frac{8}{8} + 9 \frac{7}{7}= 11+10=21
4)15 \frac{7}{18} + \frac{5}{18} +11 \frac{8}{9}+ \frac{4}{9} = 15 \frac{12}{18} +11 \frac{12}{9}=15 \frac{2}{3} +12 \frac{1}{3} =27 \frac{3}{3}=28