`8``frac{2}{7}``-``(``3``frac{4}{9}``+``4``frac{2}{7}`
`=``frac{58}{7}``-``(frac{31}{9}``+``frac{30}{7})`
`=``frac{58}{7}``-``frac{31}{9}``-``frac{30}{7}`
`=``frac{58}{7}``-``frac{30}{7}``-``frac{31}{9}`
`=``frac{28}{7}``-``frac{31}{9}`
`=``frac{252}{63}``-``frac{217}{63}`
`=``frac{35}{63}`
`=``frac{5}{9}`