a)
54:(4\frac{1}{2}*1\frac{1}{2})-2\frac{7}{8}=54:(\frac{9*3}{2*2})-2\frac{7}{8}=
=54:\frac{27}{4}-2\frac{7}{8}=54*\frac{4}{27}-2\frac{7}{8}=8-2\frac{7}{8}=5\frac{1}{8}
…
b)
(8-1\frac{3}{7}*4\frac{2}{3}):1\frac{1}{6}=(8-\frac{10*14}{7*3}):\frac{7}{6}=
=(8-\frac{20}{3})*\frac{6}{7}=(\frac{24}{3}-\frac{20}{3})*\frac{6}{7}=
=\frac{4}{3}*\frac{6}{7}=\frac{8}{7}=1\frac{1}{7}