Two students need to pull on heavy sleigh to pull it out of a rough patch of snow. One child exerts a maximum force of 40.0 N and another 58.0 N, on ropes, to just get the sleigh to move. The angles the horizontal ropes make with the direction of travel are 30 and 20, respectively. If the sleigh's mass is 75 kg, and the sleigh moves in a straight line, what is the coefficient of static friction between the sleigh and the snow?