15. \((3\frac{1}{2}-2\frac{1}{4})\times(\frac{5}{6}+\frac{2}{3})\div1\frac{1}{2}\)

\[3\frac{1}{2}-2\frac{1}{4}=\frac{7}{2}-\frac{9}{4}=\frac{5}{4}\]

\[\frac{5}{6}+\frac{2}{3}=\frac{5}{6}+\frac{4}{6}=\frac{3}{2}\]

\[\frac{5}{4}\times\frac{3}{2}\div\frac{3}{2}=\frac{5}{4}\]

Ответ: \(\frac{5}{4}=1\frac{1}{4}\).