Answer:
555x²
Step-by-step explanation:
If the height is 555 and the width is, as you say in your comment, x², then the area is the multiplication of that.

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Factorise a² - b² :
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Crossed out common factors, (x + a) :
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Answer:
23
Step-by-step explanation:
substitute x = 4 into the expression
5x + 3 = 5(4) + 3 = 20 + 3 = 23
Answer:
15
Step-by-step explanation:
15 can go into 90, 6 times. It is neither a multiple of 6 or 9. It is larger than 10 and smaller than 20.