The formula for distance is [tex]distance = rate \times time[/tex]. If you want to find rate, then manipulate that formula by dividing both sides by time to get [tex]rate = \frac{distance}{time} [/tex].
The question asks you to find the rate the team canoed. That means you have to divide the distance they rowed in miles by how long they rowed in hours.
To divide by hand, you have to convert each of your mixed numbers into improper fractions:
1) Convert 15 3/4 miles. Multiply the denominator of the fraction part, 4, by the whole number part, 15: 4*15 = 60. Add the numerator of the fraction part, 3, to that number: 60+3 = 63. Put that number over the denominator of the fraction part, 4, to get your improper fraction: 63/4. That means 15 3/4 miles = 63/4 miles.
2) Convert 2 1/4 hours using the same process as above. Multiply the denominator and the whole number: 2*4 = 8. Add the numerator to that number: 8+1 = 9. Put that number over the denominator: 9/4. That means 2 1/4 hours = 9/4 hours.
Now you can plug 63/4 miles and 9/4 hours into your equation for rate. Remember that dividing by a fraction is the same as multiplying by the inverse of that fraction:
[tex]rate = \frac{distance}{time}\\
rate = \frac{ \frac{63}{4} }{ \frac{9}{4} }\\
rate = \frac{63}{4} \div \frac{9}{4}\\
rate = \frac{63}{4} \times \frac{4}{9}
rate = \frac{63}{9}\\
rate = 7 \frac{miles}{hour} [/tex]
Your final answer is 7 mi/hr.
