A company produces two products, A and B. The sales volume for product A is at least 60% of the total sales of the two products. Both products use the same raw material, of which the daily availability is limited to 100kg. Products A and B use this raw material at the rates of 2kg/unit and 4kg/unit, respectively. The sales prices for the two products are $20 and $35 per unit respectively. Formulate a linear programming model for this problem first and then solve this model by using graphical method. Make sure the results are accurate to two decimal places!