Basically the question is asking YOU when you hear “system of equations” what do you think about it - what do you already know about system of equations. Basically. Btw enjoy this picture.
You are comparing velocities. Without a given acceleration, the time can not be found.
Answer:
4≠5
There is no solution
Step-by-step explanation:
The vertices of the quadrilateral ABCD lie on the sides of quadrilateral PQRS then the sum of the degree of measures of the eight indicated angles would be 360.
Answer: (D) 
Explanation:

Just a note on writing down these expressions: I recommend using parentheses whenever you can to avoid misinterpretation. An expression 1/x-1/y / 1/x+1/y could be interpreted by someone as 1/x-(1/y / 1/x)+1/y, which is a different thing.