Answer:
The force is  [tex]F = 2400 \ N[/tex]
Explanation:
The diagram for this question is shown on the first uploaded image
 From the question we are told that
  The mass of the dancer is  [tex]m_d = 60 \ kg[/tex]
From the diagram the
   The first distance is [tex]l_1 = 20 \ cm[/tex]
   The second distance is  [tex]l_2 = 5 \ cm[/tex]
At equilibrium the moment about the center of the dancers  feet  is mathematically represented as
   [tex]F * l_2 - (mg* l_1)[/tex]
  Where [tex]g= 10 \ m/s^2[/tex]
substituting values
   [tex]F * 5 - (60* 9.8 * 20)[/tex]
=> Â Â [tex]F = \frac{60 * 10 * 30}{5}[/tex]
=> Â Â Â [tex]F = 2400 \ N[/tex]
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