\(a,\) \(\frac{7}{8}=\frac{1+2+4}{8}=\frac{1}{8}+\frac{2}{8}+\frac{4}{8}=\frac{4}{32}+\frac{4}{16}+\frac{4}{8}\)
\(\text{b,}\) \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right).\left(1-\frac{1}{5}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}\)
\(=\frac{1}{5}\)
B)(1-1/2).(1-1/3).(1-1/4).(1-1/5)
= (2/2-1/2).(3/3-1/3).(4/4-1/4).(5/5-1/4)
=1/2.2/3.3/4.4/5
=1.2.3.4/2.3.4.5=1.2.3.4/2.3.4.5=1/5