As given in the figure below $PR$ and $SQ$ are the Speed-time graph for given two cars with initial speeds $52 \,km\,h^{-1}$ and $3\, km\,h^{-1}$ respectively.

Distance Travelled by first car before coming to rest $=$ Area of $\Delta OPR $

$=(1 / 2) \times OR \times OP$

$=(1 / 2) \times 5\, s \times 52\, km\,h^{ -1}$

$=(1 / 2) \times 5 \times(52 \times 1000) / 3600) \,m$

$=(1 / 2) \times 5 \times(130 / 9) \,m$

$=325 / 9 \,m$

$=36.11\, m$

Distance Travelled by second car before coming to rest $=$ Area of $\Delta OSQ $

$=(1 / 2) \times O Q \times OS$

$=(1 / 2) \times 10\, s \times 3 \,km\,h^{ -1}$

$=(1 / 2) \times 10 \times(3 \times 1000) / 3600) \,m$

$=(1 / 2) \times 10 \times(5 / 6) \,m$

$=5 \times(5 / 6)\, m$

$=25 / 6 \,m$

$=4.16\, m$