Question

As an estimation we are told 5 miles is 8 km.
Convert 42.5 miles to km.

Answer 1

        $\text{It is given that 5}\: miles = 8 \: km$

$\implies \: 1\: mile = \dfrac85 \: km = 1.6 \: km$

$\implies 42.5 \: miles = 1.6 \times 42.5 = 68 \: km$

$\implies \: \boxed{42.5 \: miles = 68 \: km}$