Answer:
Answer 1: a. Moonlight: C=75n+1000
Riverside: C=50n+1500
Answer 2: c. The solution coordinates are c. (20, 2500)
Answer 3: c. When there are 20 guests attending the price is $2500.
Step-by-step explanation:
Moonlight Hall:
Fixed cost = $1000
Cost per guest = $75
Cost of <em>'n' </em>guests = 75 
Total cost of moonlight hall = Fixed cost + Cost of 'n' guests

Riverside Hall:
Fixed cost = $1500
Cost per guest = $50
Cost of <em>'n' </em>guests = 50 
Total cost of moonlight hall = Fixed cost + Cost of 'n' guests

Hence, Answer 1:
a. Moonlight: C=75n+1000
Riverside: C=50n+1500
Answer 2: Coordinates of solution:
Option c. (20,2500) satisfies both the equation.
When there are 20 number of guests, the cost of both moonlight and riverside hall comes out to be 2500.
Moonlight Hall cost

Riverside Hall cost

Answer 3: c. When there are 20 guests attending the price is $2500.
The solution is done in Answer 2.
So,
Answer 1: a. Moonlight: C=75n+1000
Riverside: C=50n+1500
Answer 2: c. The solution coordinates are c. (20, 2500)
Answer 3: c. When there are 20 guests attending the price is $2500.