tìm x:
a,\(\frac{x}{2\times5}+\frac{x}{5\times8}+\frac{x}{8\times11}+\frac{x}{11\times14}=\frac{3}{7}\)
b, \(50\%+\frac{2}{3}x=x+4\)
c,\(0,5x-\frac{2}{3}\left(x+1\right)=\frac{-1}{12}\)
d,\(\frac{1}{2}\left(x-\frac{2}{3}\right)-\frac{2}{5}\left(2-x\right)=\frac{1}{9}\)
a.x=3
b.x=-21/2
c.-7/2
d.112/81