[tex]45000 \: m \times \frac{1 \: km}{1000 \: m} [/tex]
45 km in the 2nd hour
[tex]7500000 \: cm \times \frac{1 \: m}{100 \: cm} \times \frac{1 \: km}{1000 \: m } [/tex]
75 km in the 3rd hour
[tex] \frac{(75 - 30)}{(3 - 1)} [/tex]
22.5 km/h
//
I tried.