какую часть от числа z составляет число х если: х= 1/3 (40 1/7 - 38 1/3)÷2 5/7 и z= (51,4-50,8)×20/27

x= \frac{1}{3} (40 \frac{1}{7} - 38 \frac{1}{3}):2 \frac{5}{7} =\frac{1}{3} (40+ \frac{1}{7} - 38 - \frac{1}{3}): \frac{19}{7} = \\ =\frac{1}{3} (2+ \frac{3}{21} - \frac{7}{21})* \frac{7}{19} =\frac{1}{3} (2 - \frac{4}{21})* \frac{7}{19}=\frac{1}{3} *\frac{38}{21}* \frac{7}{19}=\frac{1}{3} *\frac{2}{3}=\frac{2}{9}z= (51,4-50,8)* \frac{20}{27}=0,6*\frac{20}{27}=\frac{6}{10}*\frac{20}{27}= \frac{4}{9}  \frac{x}{z} =\frac{2}{9}:\frac{4}{9}=\frac{2}{9}:\frac{9}{4}=\frac{1}{2}