If the weight of 90 books is 50kg, what is the weight of 180 such books. In both proportion and unitary method.

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Step-by-step explanation:

From the question, we are informed that the weight of 90 books is 50kg. We need to get the weight of a book first and this will be:

= 50/90

= 5/9

Therefore, the weight of 180 such books will be 5/9 multiplied by 180. This will be:

= 5/9 × 180

= 100kg

when rotating a figure 180 degrees, imagine that you are able to take the figure and turn it clockwise or counterclockwise around a center point. to rotate a figure 180 degrees, you will need to apply the rule (x, y) → (-x, -y). start by using a coordinate grid with coordinates for each vertex of the figure. the center point of the coordinate grid is located at (0, 0), which is what you will rotate the figure around. write down the original coordinates of the shape you are going to rotate. then, apply the rule. for example, coordinate (1, 2) becomes (-1, -2). another example would be, coordinate (-4, -2) becoming (4, 2). after you change each original coordinate to the rotated coordinate, you will draw your new figure.

step-by-step explanation:

pi x^2

step-by-step explanation:

pi times x squared