7. Найдите сумму дробей: 1) 2/3 + 2/11 + 1/3 + 4/11; 2) 3/5 + 3/25 + 1/5 + 7/25; 3) 5/12 + 23/75 + 38/75 + 7/12 + 14/75; 4) 1/14 + 20/77 + 3/28 + 13/77 + 11/28.

1. \(\left(\frac23+\frac13\right)+\left(\frac2{11}+\frac4{11}\right)=1+\frac6{11}=\frac{17}{11}\).
2. \(\frac45+\frac{10}{25}=\frac45+\frac25=\frac65\).
3. \(\left(\frac5{12}+\frac7{12}\right)+\frac{23+38+14}{75}=1+1=2\).
4. \(\frac1{14}+\frac3{28}+\frac{11}{28}+\frac{20}{77}+\frac{13}{77}=1\).

Ответ: 1) \(\frac{17}{11}\); 2) \(\frac65\); 3) 2; 4) 1.