Abus seems to be travelling slower when our bus overtake other, but the bus seems to be travelling fast when it is coming from the opposite direction, why

It is due to the relative velocity.

When you go opposite, the velocities of both buses get added increasing relative velocity

When we overtake it (in same direction) then the velocities get subtracted. Hence reducing relative velocity

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards