Final answer:
Derek will have earned $98 after walking dogs for a total of 7 hours using unit rates.
Step-by-step explanation:
To find out how much money Derek will have earned after walking dogs for a total of 7 hours, we can use unit rates. From the given information, we know that Derek earned $70 for 5 hours of walking dogs. So, his unit rate (rate at which he earns money per hour) is $70/5 = $14 per hour. Therefore, we can calculate the total amount of money he will earn by multiplying his unit rate by the total hours.
Therefore, after walking dogs for 7 hours, Derek will have earned $14 × 7 = $98.
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