correct answer is : c) 40 km and 32 km, after 4 hours

Explanation

Let the time will be ‘x’ hours when they meet each other.
We know,
Distance = speed\ \times\ time
Here, 1^st friend speeds are 10 km/hour.
\therefore Distance covered by 1^st friend is = \left(x\ \times\ 10\right) km
= 10x km.
And 2^nd friend speeds are 8 km/hour.
\therefore Distance covered by 2^nd friend is = \left(x\ \times\ 8\right) km
= 8x km
According the question,
\rightarrow\ 10x\ +\ 8x\ =\ 72 km
\rightarrow\ 18\ x\ =\ 72
\rightarrow\ x\ =\ \frac{72}{18}
\rightarrow\ x\ =\ 4
\therefore The time will be 4 hours when they meet each other.
And Distance covered by 1^st friend is = \left(10\ \times\ x\right) km.
= \left(10\ \times\ 4\right) km. _{[x = 4]}
= 40 km
And Distance covered by 2^nd friend is = \left(8\ \times\ x\right) km.
= \left(8\ \times\ 4\right) km. _{[x = 4]}
= 32 km
Ans: They will meet 40 km from the starting point of the first friend and 32 km from the starting point of the second friend after 4 hours.