Respuesta :

amyseal
The sum of forces = mass x acceleration

Ignoring all resisting forces like friction and air resistance, the only force is gonna be the one pushing the skier

So, 
Force = mass x acceleration

Now, we substitute the values given

Force = 68 x 1.2

And therefore, Force = 81.6 N

Don't hesitate to ask further questions!
Hope I helped! xx