Answer:
40 copies for $3000
Step-by-step explanation:
First: The Equation
y=(20+x)(100-x)
This shows how for every new painting, the price will go down.
y=2000+80x-x²
Convert it to standard form: ax²+bx+c
You can now choose to graph it or find the vertex form. For the limit of time, I will just use a graph.
The vertex, (40,3000), is your answer, where the x value is the number of paintings and the y value the money made.
Her investment was $4500. To get this, you take 1890 and divide it by 7, giving you 270. This is 6% of 4500. To prove this, you would multiply 4500 by .06, giving the answer of 270, which can then be multiplied by 7 (years) to equal $1890.
The orange (second) one. Using Pythagorean theorem the side is sqrt(100-47) which is sqrt(53)