Question

ME AJUDEEEEEM

Answer 1

Subida:

$v=20~km/h\\\Delta S = x\\\Delta t=t_{1}\\\\v=\Delta S / \Delta t_{1}\\20=x/t_{1}\\20*t_{1}=x\\t_{1}=(x/20)~h$

Descida:

$v=40~km/h\\\Delta S = x\\\Delta t=t_{2}$

$v=\Delta S/ \Delta t\\40=x/t_{2}\\40*t_{2}=x\\t_{2}=(x/40)~h$
_______________________

Subida e descida:

$v=?\\\Delta S = x+x=2x\\\Delta t= t_{1}+t_{2}=(x/20)+(x/40)=(2x/40)+(x/40)=(3x/40)~h$

$v=\Delta S / \Delta t\\v=2x/(3x/40)\\v=2x*(40/3x)\\v=(80/3)~km/h$