Various exam questions help!

[inneedoftherapy]

Hi guys
I have a few questions from various exams. 
(Since somehow I'm exceeding the limit, I'll attach the files in the comments section below? Stay tuned?)

With attachment titled "linea q" , i was wondering how to do this question.

with the attachment titled "matrices q" I was wondering (even though I agree the answer is A, I was wondering why can't it also be E, I was thinking about it and it just seemed to make sense to me) Please explain why its wrong?!

Thanks so much !!!

[inneedoftherapy]

Matrices Q

[shadows]

just to let you know. the pics are too blurry. can't see anything D:

[inneedoftherapy]

Is there another way to attach these, the files are either too big or the pcutres come out blurry

[Stevensmay]

Try something like imgur.com

[inneedoftherapy]

matrices

[inneedoftherapy]

Oh yay! I figured out a way ahhah
and here's the linear question!

[plato]

Oh yay! I figured out a way ahhah
and here's the linear question!

I think asking for four constraints here is a little confusing. I get two for b and two for c but then can eliminate one for each of b and c since the remaining inequation basically negates the need for the eliminated one.

The number of brake and clutch repairs are each constrained by the number of qualified hours (3 x 38 = 114) and apprentice hours (also 3 x 38 = 114) available in a week.
Brake repairs - 3 qualified hours each -
                      - 2 apprentice hours each -
    The over-riding constraint for the number of brake repairs must be

Clutch repairs - 3 qualified hours each -
                       - 4 apprentice hours each -
    The over-riding constraint for the number of clutch repairs must be since you cannot have half a clutch repair if we assume that no job can carry over into the next week.

While not asked for here, the information given leads to a profit equation of P = 75b + 120c