In every panel the farm produces where price, which is marginal revenue for a price taker, equals marginal cost. Whether that output is profitable depends on average cost. In (a), at $5, the farm produces about 85 packs and average cost there is about $3.50, so the shaded rectangle, (price − average cost) × quantity, is profit of roughly $127. In (b), at $2.75, price meets marginal cost right where marginal cost crosses the minimum of average cost, so profit is zero: the break-even point.
In (c), at $2.00, the farm produces about 65 packs but average cost there is about $2.73, so the rose rectangle is a loss of about $47. The three sliders set the price in each panel; the shading turns from blue profit to rose loss as the price drops through average cost.