I would say C but number 2 isn’t making sense but 1 and 3 are true
Answer:
x= 22.5
Step-by-step explanation:

So the question is the original price was $791 and they bought it at the marked down price at $474.60? then they saved $316.40 but i’m not really sure if that’s the question lol
Both functions are the solution to the given Laplace solution.
Given Laplace's equation: 
- We must determine whether a given function is the solution to a given Laplace equation.
- If a function is a solution to a given Laplace's equation, it satisfies the solution.
(1) 
Differentiate with respect to x as follows:

Differentiate with respect to y as follows:

Supplement the values in the given Laplace equation.

The given function in this case is the solution to the given Laplace equation.
(2) 
Differentiate with respect to x as follows:

Differentiate with respect to y as follows:

Substitute the values to obtain:

The given function in this case is the solution to the given Laplace equation.
Therefore, both functions are the solution to the given Laplace solution.
Know more about Laplace's equation here:
brainly.com/question/14040033
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The correct question is given below:
Determine whether each of the following functions is a solution of Laplace's equation uxx + uyy = 0. (Select all that apply.) u = e^(−x) cos(y) − e^(−y) cos(x) u = sin(x) cosh(y) + cos(x) sinh(y)
P: Parenthesis
E: Equation
M:Multiplication
D: Division
A : addition
S: Subtraction
So first you need to divide because it is before so you divide 18 by 6 which is 3 then you subtract (31 - 3) which gives you 28
answer : 28