PTA = BTQ (vertically opposite angles are equal)
APT = BQT (equal right angles... not really sure how to say it)
PAT = TBQ (remaining angles equal?)
Therefore triangle PAT is similar to triangle QTB (Equiangular)
I think internal influences includes all the things which the business has some degree of control of. E.g. employees, legal structure, management styles etc.
and external influences includes all the things which the business has very little control over. E.g. economic conditions, competition...
Those are some weird questions... I don't how your meant to do it, and I didn't actually have a proper way (I think I guessed some random values) but if the tank can fill 20L and the big pipe goes at a rate of 10L/hr and the small pipe goes at a rate of 5L/h, then the big pipe can fill it in 120...