We are given the retail price of desk as $320. The store takes 50% off of the retail price of desk, then its price would become half of the original.
So its new price would be $160.
Now it says that it takes an additional 20% off of all furniture on store's holiday sale. So we need to cut off 20% from new price $160.
Holiday discount = 20% of $160 = 0.2 × 160 = 32.
Final selling price would be = $160 - $32 = $128.
So $128 is the final answer.
Answer: 
<u>Step-by-step explanation:</u>
y = A cos (Bx - C) + D
- A (amplitude) = max - D
- B = Period/2π ---> Period is the distance from max to next max
- C = B · Phase Shift ---> Phase shift is distance from y-axis to max
- D (vertical shift) = (max + min)/2
D = (max + min)/2 = (3 - 11)/3 = -4
A = max - D = 3 - (-4) = 7
Period = 9π/4 - π/4 = 8π/4 = 2π
B = Period/2π = 2π/2π = 1
Phase Shift = π/4 - 0 = π/4
C = B · Phase Shift = 1 · π/4 = π/4
Equation:
y = 7 cos (1·x - π/4) + (-4)
Assume x are Erica's classes & y are Bo's classes.
x+y=35
x=2y-13
Replacing the value of x into the first equation
2y-13+y=35
3y=35+13
y=16 classes
x=2*16-13=19 classes