1) (−2,5)² − (−3,2) · (−3/8) + (−6,25); 2) −3 1/3 · (−2 3/4 · 5 1/2) + 2 2/5 : (−1 11/15).

\[(-2.5)^2-(-3.2)\cdot\left(-\frac{3}{8}\right)+(-6.25)=6.25-1.2-6.25=-1.2.\]

Ответ: \(-1,2\).

\[-3\frac{1}{3}=-\frac{10}{3},\quad -2\frac{3}{4}=-\frac{11}{4},\quad 5\frac{1}{2}=\frac{11}{2},\quad 2\frac{2}{5}=\frac{12}{5},\quad -1\frac{11}{15}=-\frac{26}{15}.\]

\[-\frac{10}{3}\cdot\left(-\frac{11}{4}\cdot\frac{11}{2}\right)+\frac{12}{5}:\left(-\frac{26}{15}\right)=\frac{605}{12}-\frac{18}{13}=\frac{7649}{156}.\]

Ответ: \(\frac{7649}{156}=49\frac{5}{156}\).