$1\text{ km}=1000\text{ m}$

$8\text{ km}$ = $8000\text{ m}$

$1{\text{ cm}}^2=100{\text{ mm}}^2$

$\mathrm{3,12}{\text{ cm}}^2$ = $312$${\text{ mm}}^2$

$60\min =1$h

$150$ min = $\mathrm{2,5}$ h