\(x +x\cdot\frac{1}{4}\text{ : }\frac{2}{7}+x\text{ : }\frac{2}{9}=255\)
\(x+x\cdot0,25\text{ : }0,285714286+x\text{ : }0,222222222=255\)
\(x+x\cdot\left(0,25\text{ : }0,285714286\right)+x\text{ }\text{ : }0,222222222=255\)
\(x+x\cdot0,874999999+x\text{ : }0,222222222=255\)
\(x\cdot3\cdot\left(0,874999999\text{ : }0,222222222\right)=255\)
\(x\cdot3\cdot3,9375=255\)
\(x\cdot3=255\text{ : }3,9375\)
\(x\cdot3=64,7619048\)
\(x=64,7619048\text{ : }3\)
\(x=21,5873016\)