#-242/21 color(red)(+ 8) = -9/4 x + 1/3 color(red)(cancel(color(black)(- 8) color(red)( + 8)#
#-11 11/21 + 8 = -9/4 x + 1/3#
#-3 11/21 -1/3 = -9/4 x color(red)(cancel( color(black)(+ 1/3) color(red)(-1/3)#
#-3 11/21 -7/21 = -9/4 x#
#-3 18/21= -9/4 x#
#-3 6/7 color(red)(÷ -9/4)= color(red)(cancel(color(black)(-9/4) color(red)(÷ -9/4)) x#
#x = -3 6/7 ÷ -9/4#
#x = -3 6/7 xx -4/9#
#color(blue)(x = 1 5/7#
We can now substitute #1 5/7# for #x# in the equation to prove our answer.
#-242/21 = -9/4 x + 1/3 - 8#
#-242/21 = -9/4 xx 1 5/7 + 1/3 - 8#
#-242/21 = -3 6/7 + 1/3 - 8#
#-242/21 = -3 11/21 - 8#
#-242/21 = -11 11/21#
#-242/21 = -242/21#