Question

please send solutions

Answer 1

Let v is the speed of boy
Let s is the distance
and t is the time then
s=v×t
if he increase his speed by 3km/min then
s={v+3}{t-40}. 1st equation
if he decrease his speed by 2km/min then
s={v-2}{t+40}. 2nd equation
from 1st and 2nd equation
$\frac{v + 3}{v - 2 } = \frac{t + 40}{t - 40}$
on solving we get,
$v = \frac{t - 8}{16}$