Answer:
72 km/hr
Step-by-step explanation:
The division of fractions is carried out in any of the usual ways. The ratio of units multiplies the result.
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[tex]\dfrac{20\div1000\text{ km}}{1\div1000\text{ hr}}=\dfrac{20}{1000}\div\dfrac{1}{3600}\cdot\dfrac{\text{km}}{\text{hr}}=\dfrac{20}{1000}\cdot\dfrac{3600}{1}\cdot\dfrac{\text{km}}{\text{hr}}\\\\=\boxed{72\ \dfrac{\text{km}}{\text{hr}}}[/tex]
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Additional comment
The multiplication of fractions is shown here using the "invert and multiply" method. This makes use of the fact that division is the same as multiplication by the reciprocal.
