She started with 81 baseball cards.
Answer:
D
Step-by-step explanation:

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Factor out 2 on the numerator and 2x on the denominator.
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Cancel the factor (x + 2) on the numerator/ denominator
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← cancel the 2 on numerator/ denominator
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: x ≠ 0
Answer:
The area of the rectangular deck is 36 sq feet.
Step-by-step explanation:
Let the width of the deck = k ft
So, the length of the deck = (4k) ft
Now, perimeter = 30 ft
PERIMETER OF A RECTANGLE = 2(LENGTH + WIDTH)
⇒2( k + 4k) = 30
or, 2 x 5k = 30 ⇒ 10k = 30
⇒ k = 30/10 = 3
So, the width of the deck = k = 3 ft
Length of the deck = 4k = 3 x 4 = 12 ft
Now, AREA OF A RECTANGLE = LENGTH X WIDTH
So, the area of the rectangular deck = 3 ft x 12 ft
= 36 sq feet
Hence, the area of the rectangular deck is 36 sq feet.
A^2 + b^2 = c^2
9^2 + b^2 = 15^2
81 + b^2 = 225
225 - 81 = b^2
144 = b^2
square root of 144 = 12
b = 12