First, put the fraction on the left over a common denominator with the fraction on the right by multiplying the fraction on the left by the appropriate form of #1#:
#(2/2 xx 4/7x) + 5/14x = 39#
#8/14x + 5/14x = 39#
Next, factor out the common term on the left side of the equation and add the fractions over the common denominator:
#(8/14 + 5/14)x = 39#
#(8 + 5)/14x = 39#
#13/14x = 39#
Now, multiply each side of the equation by #color(red)(14)/color(blue)(13)# to solve for #x# while keeping the equation balanced:
#color(red)(14)/color(blue)(13) xx 13/14x = color(red)(14)/color(blue)(13) xx 39#
#cancel(color(red)(14))/cancel(color(blue)(13)) xx color(blue)(cancel(color(black)(13)))/color(red)(cancel(color(black)(14)))x = color(red)(14)/color(blue)(13) xx (3 xx 13)#
#x = color(red)(14)/cancel(color(blue)(13)) xx (3 xx color(blue)(cancel(color(black)(13))))#
#x = 14 xx 3#
#x = 42#
