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 

Answer:
can you show us the graph
Answer for this question is the zeros are greater than -4 and 2
A. Is the attached image. The slope is 7.5x
b. 1 = 7.5x
x = 1.33333…
This is hours so we must multiply this by 60
x = 8 min