It should be option A! I hope this helps you!
Perimeter is adding the 3 sides together. Since both triangles have the same perimeter set both triangles to equal:
(x+3 + x+3 + x+3) = (x+3 + 2x-3 + x)
Simplify each side:
3x+9 = 4x
Subtract 3x from each side:
x=9
The graph line will drop down by 12. meaning your initial cost (without any labor and material costs) goes down by 12, since your unit is in thousands
Let A be the event 
and B be the vent 
. Since the intersection of the events 
, the events A and B are mutually exclusive.
The number is either odd or even. Since 
, the events are mutually exclusive and exhaustive.
Correct choice is "the number is either odd or even".
