3. Өрнектің мәнін табыңдар: 1) (−2,6 + 4,5) + (2,8 + (−0,9)); 2) (−5 3/7 + 5 1/14) + (5/7 + (−5/14)).

1. \( (-2.6+4.5)+(2.8-0.9)=1.9+1.9=3.8 \).
2. \( \left(-5\frac{3}{7}+5\frac{1}{14}\right)+\left(\frac{5}{7}-\frac{5}{14}\right) \)
   \(=\left(-\frac{38}{7}+\frac{71}{14}\right)+\left(\frac{10}{14}-\frac{5}{14}\right) \)
   \(=-\frac{5}{14}+\frac{5}{14}=0 \).

Жауабы: 1) 3,8; 2) 0.