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99 points at a zoo, the leopard pen has a ring-shaped sidewalk around it. the outer edge of the sidewalk is a circle with a radius of 12 m. the inner edge of the sidewalk is a circle with a radius of 8 m. (1 point for showing all of your work) a. write and simplify an expression for the exact area of the sidewalk. (1 point for the answer) b. find the approximate area of the sidewalk. use 3.14 to approximate π. (1 point for the answer)

What is 140% of 25? because i need

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years