In order to at least earn $90, Katie can work exercising horses for 6 hours and cleaning stalls for 6 hours.
Step-by-step explanation:
Let hours of exercising horses be x --> $5 per hour = 5x
Let hours of cleaning stalls be y --> $10 per hour = 10y
Total earning = 
Total hours = 12
<u>Equation 1:</u>
5x + 10y = 
<u>Equation 2:</u>
x + y 
<em>1. Multiply equation 2 by -5</em>
x + y
(*-5)
5x + 10y = 
-5x - 5y
5x + 10y = 
<em>2. Solve</em>
-5x + 5x -5y + 10y = -60 + 90
5y = 30
y = 6
x + y = 12
x + 6 = 12
x = 6
Therefore, in order to at least earn $90, Katie can work exercising horses for 6 hours and cleaning stalls for 6 hours.
Keywords: Simultaneous, hours, equations
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Chris baked 95 cookies.
Step-by-step explanation:
Given,
Cookies baked by Haley = 50
Cookies baked by Chuck = 65
Cookies baked by Dana = 90
Average of them = 75
Let,
Cookies baked by Chris = x
Average = 

Multiplying both sides by 4

Chris baked 95 cookies.
Keywords: addition, average
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Answer:
Now I am not completely sure but...maybe is it that:
A quadratic regression is the process of finding the equation of the parabola that best fits a set of data. As a result, we get an equation of the form:
y = a x 2 + b x + c where a ≠ 0 .
Cause I think it might be the best way to find this equation manually is by using the least squares method. That is, we need to find the values of a , b , and c such that the squared vertical distance between each point ( x i , y i ) and the quadratic curve y = a x 2 + b x + c is minimal.
The matrix equation for the quadratic curve is given by:
[ ∑ x i 4 ∑ x i 3 ∑ x i 2 ∑ x i 3 ∑ x i 2 ∑ x i ∑ x i 2 ∑ x i n ] [ a b c ] = [ ∑ x i 2 y i ∑ x i y i ∑ y i ]