Algebra-2

Let's first convert the time difference from minutes to hours since the speeds are usually measured in miles per hour.

We know that  minutes  hours.

Let's assume Grace's speed is  miles per hour. Then Liam's speed is  miles per hour.

We use the formula , where  is the time taken,  is the distance, and  is the speed.

For Grace, who swims a distance  miles at a speed of  miles per hour, the time taken  hours.

For Liam, who swims the same distance  miles at a speed of  miles per hour, the time taken  hours.

We are given that it takes Liam  hours less than Grace to complete the swim. So we can set up the following equation:

To get a common denominator, we multiply the first fraction by  and the second fraction by :

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