Вычислите значения выражений: 1) (7/12)a + (3/12)a, a = 12; 2) (4/7)a + (6/7)a, a = −7; 3) (5/6)a − (1/6)a, a = 6; 4) (1/55)a + (5/55)a, a = −11; 5) (2/5)a + (3/5)a, a = 2; 6) (12/15)a − (7/15)a, a = −3; 7) (40/57)a + (17/57)a, a = 1; 8) (6/7)a + (2/7)a, a = 7; 9) (3/7)a + (2/7)a, a = −7; 10) (11/25)a − (6/25)a, a = 5; 11) (4/5)a − (3/5)a, a = −5; 12) (7/11)a + (9/11)a, a = 11; 13) (7/8)a − (5/8)a, a = −4; 14) (5/9)a + (4/9)a, a = 3.

1. \(\left(\frac{7}{12}+\frac{3}{12}\right)\cdot12=10\).
2. \(\left(\frac{4}{7}+\frac{6}{7}\right)\cdot(-7)=-10\).
3. \(\left(\frac{5}{6}-\frac{1}{6}\right)\cdot6=4\).
4. \(\left(\frac{1}{55}+\frac{5}{55}\right)\cdot(-11)=-\frac{6}{5}\).
5. \(\left(\frac{2}{5}+\frac{3}{5}\right)\cdot2=2\).
6. \(\left(\frac{12}{15}-\frac{7}{15}\right)\cdot(-3)=-1\).
7. \(\left(\frac{40}{57}+\frac{17}{57}\right)\cdot1=1\).
8. \(\left(\frac{6}{7}+\frac{2}{7}\right)\cdot7=8\).
9. \(\left(\frac{3}{7}+\frac{2}{7}\right)\cdot(-7)=-5\).
10. \(\left(\frac{11}{25}-\frac{6}{25}\right)\cdot5=1\).
11. \(\left(\frac{4}{5}-\frac{3}{5}\right)\cdot(-5)=-1\).
12. \(\left(\frac{7}{11}+\frac{9}{11}\right)\cdot11=16\).
13. \(\left(\frac{7}{8}-\frac{5}{8}\right)\cdot(-4)=-1\).
14. \(\left(\frac{5}{9}+\frac{4}{9}\right)\cdot3=3\).

Ответ: 10; −10; 4; −6/5; 2; −1; 1; 8; −5; 1; −1; 16; −1; 3.