56m^2
see the steps from the pic
M các ma trận vuông cấp hai thỏa mãn
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Answer:
<em>Total Cost at Amy's shop is $280 which is less than the total cost at Mike's shop which is $295, so I will take the car to Amy's shop</em>
<em>Point of intersection: (x,y) = (4,360)</em>
Explanation:
Part 1 )
Let x = number of hours worked
Let y = total cost to you
Determining where to take the car:
<em>Total Cost at Amy's shop is $280 which is less than the total cost at Mike's shop which is $295</em>
Mike's repair shop:
Service fee: $100
Per hour rate: $65
Let x is the number of hours worked on. Total cost will be equal to the service fee plus hourly charges. Charges per an hour are $65, so for x hours the charges will be 65x.
Therefore, total cost for Amy's repair shop can be written as:
y = 100 + 65x ------(1)
For 3 hours work: y = 100 + 65(3)
<em>Cost at Mike's, y = $100 + $195 = $295</em>
<em>Amy's repair shop: </em>
Service fee: $40
Per hour rate: $80
Charges per an hour are $40, so for x hours the charges will be 80x.
Therefore, total cost for Amy's repair shop can be written as:
y = 40 + 80x ------(2)
For 3 hours work: x = 3
y = 40 + 80(3)
<em>Cost at Amy's, y = $40 + $240 = $280</em>
<em>Part 2)</em>
<em>Find the point of intersection</em>
<em>Using elimination method:</em>
<em>y = 100 + 65 x ------1</em>
<em>y = 40 + 80x ------2</em>
<em>As the y coefficients are equal we will subtract eq1 from eq2</em>
<em>y - y = 40 + 80x - 100 - 65x</em>
<em>0 = -60 + 15x</em>
60 = 15x
x =
x = 4
put x = 4 in eq 1
we get y = 100 + 65 (4) = 100 + 260 = 360
x = 4, y = 360
Point of intersection: (x,y) = (4,360)