Please can you factorise this expression for me?? a(3u -v) plus a (u plus 2v) Please show working. thx in advance

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

With this question, the answer with the red arrow is incorrect!