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Start by writing a rate that compares the number of miles to hours.
D
We are asked to find how many miles per hour Debra can run. We know that she can run 20 12 miles in 2 14 hours. Let's start by writing a rate that compares the number of miles to hours.
20 12 miles/2 14 hours
We can find the how fast Debra can run by calculating the unit rate. We can do this by simplifying the expression that we got. Let's ignore the units for now.
20 12/2 14
We got that 20 12 is equal to 412. Now we will rewrite 2 14.
We found that 2 14 is equal to 94. Now we can replace the mixed numbers with improper fractions. 20 12 ÷ 2 14 = 41/2 ÷ 9/4 Next, we will write the division by 94 as multiplication by the reciprocal of 94, which is 49. 41/2 ÷ 9/4 = 41/2 * 4/9 Finally, we can evaluate the expression.
Multiply fractions
Multiply
a/b=.a /2./.b /2.
Calculate quotient
Write as a sum
Split into factors
Write fraction as a mixed number
We found that Debra can run 9 19 miles per hour. This means that D is the correct option.