So the so the product of two consecutive numbers is 4160 or
x(x+1)=4160
distribute
x^2+x=4160
subtract 4160 from both sides
x^2+x-4160=0
find the factor (if you want to know how, just ask in the comments)
(x-64)(x+65)=0
so the answer is x could be 64 or -65
so the number that work are 64,65 and -65,-64
This is a more difficult one to explain. Let's start with the line to the right. It has a slope (m) of 
= -1 and a y-intercept of +3 (continue the line to see where it crosses the y-axis). So, the equation of that line is: y = -x + 3 when x ≥ 2. This can also be written as y = 3 - x when x ≥ 2. The only option that has that equation is A.
Answer: A
I would set D = 816000 and then solve
