A herb gardener is considering growing sage and rosemary on a 40 acre farm. She has 120 hours available for planting. It takes 2 hours to plant an acre of sage and 4 hours to plant an acre of rosemary. Sage will produce a daily profit of $50 per acre while rosemary will produce a daily profit of $30. She wants to know how many acres of sage (X1) and/or rosemary (X2) to plant in order to maximize profit.