[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]
Average speed is defined as total distance covered by total time taken ~
[tex]\qquad \sf \dashrightarrow \: \dfrac{total \: distance}{total \: time} [/tex]
[tex]\qquad \sf \dashrightarrow \: \dfrac{300}{6} [/tex]
[tex]\qquad \sf \dashrightarrow \:50 \: \: kmph[/tex]