First, multiply each side of the equation by #color(red)(u)# to eliminate the fraction on the left side of the equation while keeping the equation balanced:
#11/13 xx color(red)(u) = 10/u xx color(red)(u)#
#11/13u = 10/color(red)(cancel(color(black)(u))) xx cancel(color(red)(u))#
#11/13u = 10#
Next, multiply each side of the equation by #color(red)(13)/color(blue)(11)# to solve for #u# while keeping the equation balanced:
#color(red)(13)/color(blue)(11) xx 11/13u = color(red)(13)/color(blue)(11) xx 10#
#cancel(color(red)(13))/cancel(color(blue)(11)) xx color(blue)(cancel(color(black)(11)))/color(red)(cancel(color(black)(13)))u = 130/11#
#u = 130/11#