You want to find the unit rate...how many miles in one hour. To do this we just divide the distance she walks by the time it takes her to walk that distance.
[tex]\sf 2\dfrac{1}{2}\div\dfrac{3}{4}[/tex]
Convert the mixed number into an improper fraction. We do this by multiplying the denominator to the whole number, adding it to the numerator, which becomes our new numerator, and we keep the denominator the same:
[tex]\sf \dfrac{5}{2}\div\dfrac{3}{4}[/tex]
When dividing fractions we flip(the reciprocal) the one we're dividing by and multiply:
[tex]\sf \dfrac{5}{2}\times\dfrac{4}{3}[/tex]
Multiply the numerators and denominators together:
[tex]\sf\dfrac{20}{6}[/tex]
Convert it back to a mixed number. Six goes into twenty three times. 6 * 3 = 18. 20 - 18 = 2. So we have 3 wholes and 2 left over, or:
[tex]\sf 3\dfrac{2}{6}[/tex]
We can simplify this further, divide 2 to the numerator and denominator of the fraction:
[tex]\boxed{\sf 3\dfrac{1}{3}}[/tex]
