Tracking a change over time.
Let D be dogs and C be cats
<em>dogs, d, is initially five less than twice the number of cats, c</em>
D + 5 = 2C
<em>If she decides to add three more of each, the ratio of cats to dogs will be</em>
D + 8 = 2C + 3
<em>Could Bea's Pet Shop initially have 15 cats and 20 dogs?</em>
Simply plug in the numbers
20 + 5 = 2(15)
This is clearly not true: 25 does not equal 30
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The answer would be 10a-11y
You want to be finding out what two factors (where one of them is a perfect square) has the produce of 63. It seems like 9 x 7 (9 is the perfect square) works.

The square root of 9 is 3 so we can just have

(which just means 3 times the square root of 7).
540 (100 centimeters = 1 meter, so 54 x 100 = 540.)