I NEED HELP PLEASE, THANKS! :)

  see below

Step-by-step explanation:

It can be useful to remember that the angle θ of rotation between the x-y plane and the x'-y' plane is given by ...

  cot(2θ) = (A -C)/B

where the standard form equation is ...

  Ax² +Bxy +Cy² +Dx +Ey +F = 0

For a 30° rotation, you want ...

  (A -C)/B = cot(2·30°) = 1/√3

Looking at the answer choices, you have ...

  A: (A -C)/B = (3 -(-39))/(42√3) = 1/√3 . . . as required

  B: (A -C)/B = (3 -(-39))/(-12√3) = 7/(2√3)

  C: (A -C)/B = (-39 -3)/(42√3) = -1/√3

  D: AC > 0, not a hyperbola

_____

Based on rotation angle only, the appropriate choice is the first choice. Because the term signs in the x'-y' formula are different, the figure is a hyperbola. In general form, the equation describes a hyperbola when AC<0.

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations: