Because they have the same inclination so if we try to draw them on a diagram they will be parallel to each other.
I'm assuming that you mean

because if you meant

then u would simplify and you couldn't make it the subject.
Under this assumption, we start with

We multiply both sides by 

We expand the left hand side:

We move all terms involving u to the left and all terms not involving u to the right:

We factor u on the left hand side:

We divide both sides by 

The answer would have to be 60
To determine the answer, we need to express the fractions into its decimal counterparts. 3/5 is equal to 0.6 therefore it is closest to 0.5 while 1/10 is equal to 0.1 therefore it is the last option. Hope this answers the question. Have a nice day.