Let w_1 = weight 1\n\nLet w_2 = weight 2\n\nLet d_1 = distance 1\n\nLet d_2 = distance 2\n\nI understand the equation for all lever problems to be (w_1)(d_1) = (w_2)(d_2).\n\n1. John weighs 90 lbs and Jane weighs 60 lbs. They are both seating on a seesaw. If John is seated 10 feet away from Jane, how far should each be from the fulcrum of the seesaw?\n\nI will use f for fulcrum.\n\nJohn...........f..............Jane\n\nDistance from John to f = x.\nDistance from Jane to f = 10 - x\n\nEquation\n\n90x = 60(10 - x)\n\nYes?\n\n2. John wants to move a 400 lb. rock with a 5 ft. 9 in. crowbar. He puts the fulcrum 9 inches from the rock. How much force must he use to move the rock?\n\nLet 5 feet, 9 inches be 70.8 inches.\n\nRock...........f...........x\n\nLet x = amount of force needed.\n\nDistance from Rock to f = 9.\nDistance from John to f = 70.8.\n\nEquation \n\n9(400) = 70.8x\n\nYes?