2:
=1/2+3/4-3/4+4/5
=1/2+4/5=5/10+8/10=13/10
5: =1/4+3/4*(-7/6)
=1/4-21/24
=6/24-21/24=-15/24=-5/8
8: =7/9(3/4+1/4)=7/9
11: =5/9(1/7+1/7+3/7)=5/9*5/7=25/63
14: \(=\dfrac{7}{2}\left(\dfrac{29}{13}-\dfrac{3}{13}\right)+3.12\cdot\dfrac{1}{2}\)
\(=\dfrac{7}{2}\cdot2+\dfrac{3.12}{2}\)
=7+1,56=8,56