Question

The drawing shows a circus clown who weighs 750 N. The coefficient of static friction between the clown’s feet and the ground is 0.630. He pulls vertically downward on a rope that passes around three pulleys and is tied around his feet. What is the minimum pulling force that the clown must exert to yank his feet out from under himself?

For this, I combined 2 algerbraic expressions to figure out the force. But, since I'm given such little information, I don't understand how to solve for the minimum force. Do I need to find another variable before solving this problem? Please help, thanks!