`a) 3/7+ ( -4/21) - 4/14`
`= 3/7-4/21 - 2/7`
`= 3/7 - 2/7 - 4/21 `
`= 1/7 -4/21`
`=`\(\dfrac{3-4}{21}\)
`= -1/21`
`b) -0,5 + (-3/4)+(-2/3)`
`= -0,5 - 3/4 - 2/3`
`=-1/2 - 3/4- 2/3`
`=\(\dfrac{-6-9-8}{12}\) ` `= -23/12`
`c) 1/3 - (-2 2/5) + (-3 1/4)`
`= 1/3 + 2 2/5 - 3 1/4`
`= 1/3 + 2+ 2/5 - 3 - 1/4`
`= 2-3 + 1/3 + 2/5 - 1/4`
`= - 60/60 + 20/60 + 24/60 = 15/60`
a: =3/7-2/7-4/21
=1/7-4/21
=-1/21
b: \(=\dfrac{-1}{2}-\dfrac{3}{4}-\dfrac{2}{3}=\dfrac{-6-9-8}{12}=\dfrac{-23}{12}\)
c: \(=\dfrac{1}{3}+\dfrac{12}{5}-\dfrac{13}{4}\)
\(=\dfrac{20}{60}+\dfrac{144}{60}-\dfrac{195}{60}=\dfrac{164-195}{60}=\dfrac{-31}{60}\)
