[tex]\displaystyle\bf\\1\frac{7}{8}:\left[1\frac{1}{2}-\frac{3}{4}\right]=\\\\\\=\frac{1\times8+7}{8}:\left[\frac{1\times2+1}{2}-\frac{3}{4}\right]=\\\\\\=\frac{15}{8}:\left[\frac{^{2)}3}{2}-\frac{3}{4}\right]=\\\\\\=\frac{15}{8}:\left[\frac{6}{4}-\frac{3}{4}\right]=\\\\\\=\frac{15}{8}:\frac{6-3}{4}=\frac{15}{8}:\frac{3}{4}=\frac{15}{8}\times\frac{4}{3}=\frac{15\times4}{8\times3}=\boxed{\bf\frac{5}{2}}[/tex]
