Question

It takes 5 minutes to fill an empty aquarium to a depth of 5/8 meters.
What is the unit rate in minutes per meter?

Answer 1

5 minutes / 5/8 meters

equals

X minutes / 1 meter

cross multiplies:

5 * 1 = (5/8)x

5 = (5/8)x

5*8/5 = x

x = 8

8 minutes per meter

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Here's another way to argue...

5 minutes needed for 5/8 meter

1 minute needed for 1/8 meter <--- divides the ratio by 5 on both sides

8 minutes needed for 1 meter <--- multiplies both sides of the ratio by 8 to get what you want