`a, 1/2 x = 13/5`
`=> x = 26/5`.
`b, 3/7 + 2/9 : x = 4/3`
`2/9 : x = 19/21`
`x = 14/57`.
`c, 4/3 x + -1/4 x = -7/12`
`13/12 x = -7/12`
`x = -7/13`
\(a,\dfrac{1}{2}x=2-\left(-\dfrac{3}{5}\right)\\ \dfrac{1}{2}x=\dfrac{10-\left(-3\right)}{5}\\ \dfrac{1}{2}x=\dfrac{13}{5}\\ x=\dfrac{13}{5}:\dfrac{1}{2}\\ x=\dfrac{26}{5}\\ b,\dfrac{2}{9}:x=\dfrac{4}{3}-\dfrac{3}{7}\\ \dfrac{2}{3}:x=\dfrac{4.7-3.3}{21}\\ \dfrac{2}{3}:x=\dfrac{19}{21}\\ x=\dfrac{2}{3}:\dfrac{19}{21}\\ x=\dfrac{14}{19}\\ c,x\left(\dfrac{4}{3}-\dfrac{1}{4}\right)=-\dfrac{7}{12}\\ \left(\dfrac{16-3}{12}\right)x=-\dfrac{7}{12}\\ \dfrac{13}{12}x=-\dfrac{7}{12}\\ x=-\dfrac{7}{12}:\dfrac{13}{12}\\ x=-\dfrac{7}{13}\)
