If x doesnt equal 0, then u/x+5u/x-u/5x

So basically the x is not equal to zero is so that we don't get an undifined result (division by zero is not allowed at all ever or else bad things will happen)
so add them
remember that adding fractions with same botom numbers is easy ex
(x/y)+(z/y)=(x+z)/y so
u/x+5u/x-u/5x
convert all bottom number to same
should be 5x
multiply first 2 fractions by 5/5
5u/5x+25u/5x-u/5x=(5u+25u-1u)/5x=(30u-1u)/5x=(29u)/5x

answer is (29u)/(5x)

so the answer is C