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The continental United States - the lower 48 states - has about 16,900 miles of shoreline. This is about ½ the length of the shoreline of Alaska. About how many miles of shoreline does Alaska have?

We can write a division equation to find the answer to problems like this. Our unknown number is the length of shoreline in Alaska. Let x represent this number. We know that x divided by 2 is the approximate length of shoreline in the lower 48 states. We can write the equation like this:

To solve this equation, we can use the inverse of dividing by 2, or multiplying by 2. If we multiply the left side of the equation by 2, we will get x alone on the left. Remember, any operation done to one side must also be done to the other side, so we must also multiply the right side by 2.

We multiply, and find that x, the length of the shoreline of Alaska, is equal to 33,800 miles.

To check our answer, we substitute the value of 33,800 into the original equation, like this.