[tex]7(\frac{9}{4}x- \frac{18}{7})= -\frac{5}{21} +\frac{17}{7}x <=> \frac{63}{4}x-18 =-\frac{5}{21}+ \frac{17}{7}x\\ <=>\frac{63}{4}x - \frac{17}{7}x = 18-\frac{5}{21}<=>\frac{373}{28} =\frac{373}{21} <=>x=\frac{4}{3}[/tex]
ok done. Thank to me :>
