1. Вычислите: 1) −15 + (−28); 2) 3.7 − 4.1; 3) −2.3 + 6.1; 4) −2/5 − 1/3; 5) 5/6 − (−1/4); 6) −1 1/2 + 3/4.

1. \(-15+(-28)=-43\).
2. \(3.7-4.1=-0.4\).
3. \(-2.3+6.1=3.8\).
4. \(-\frac{2}{5}-\frac{1}{3}=-\frac{6}{15}-\frac{5}{15}=-\frac{11}{15}\).
5. \(\frac{5}{6}-\left(-\frac{1}{4}\right)=\frac{5}{6}+\frac{1}{4}=\frac{10}{12}+\frac{3}{12}=\frac{13}{12}\).
6. \(-1\frac{1}{2}+\frac{3}{4}=-\frac{3}{2}+\frac{3}{4}=-\frac{6}{4}+\frac{3}{4}=-\frac{3}{4}\).

Ответ: 1) −43; 2) −0.4; 3) 3.8; 4) −11/15; 5) 13/12; 6) −3/4.