Dan is watching The Birds in his backyard. Of the birds he watches, 9. Of them, or 45%, are sparrows. How many birds are in his backyard?

Question

Mathematics

Julianna Yu

3 January, 12:40

Dan is watching The Birds in his backyard. Of the birds he watches, 9. Of them, or 45%, are sparrows. How many birds are in his backyard?

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Answers (1)

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Jesus Cortez · Answer 1

If 9 of the sparrows is 45% of the birds in the backyard, 9/x = 45/100.

Cross multiply to get 9 * 100 = 45x; simplified is 900 = 45x or 20.

This means that there are 20 birds in the backyard. You can check this by dividing 9/20 which equals 45%