15. (3 1/2 − 2 1/4) × (5/6 + 2/3) ÷ 1 1/2 =; 16. 2 1/3 × 3 1/4 + (3 1/2 − 1 5/6) ÷ 2/3 =

15. \(3\frac{1}{2}-2\frac{1}{4}=\frac{7}{2}-\frac{9}{4}=\frac{14-9}{4}=\frac{5}{4}\).

\(\frac{5}{6}+\frac{2}{3}=\frac{5}{6}+\frac{4}{6}=\frac{3}{2}\), а \(1\frac{1}{2}=\frac{3}{2}\).

\(\frac{5}{4}\cdot\frac{3}{2}:\frac{3}{2}=\frac{5}{4}\).

Ответ: \(1\frac{1}{4}\).

16. \(2\frac{1}{3}\cdot3\frac{1}{4}=\frac{7}{3}\cdot\frac{13}{4}=\frac{91}{12}\).

\(3\frac{1}{2}-1\frac{5}{6}=\frac{7}{2}-\frac{11}{6}=\frac{21-11}{6}=\frac{5}{3}\).

\(\frac{5}{3}:\frac{2}{3}=\frac{5}{3}\cdot\frac{3}{2}=\frac{5}{2}\).

\(\frac{91}{12}+\frac{5}{2}=\frac{91}{12}+\frac{30}{12}=\frac{121}{12}=10\frac{1}{12}\).

Ответ: \(10\frac{1}{12}\).