answer:# Solution: Part 1: Let x represent the increase in the selling price of the T-shirts. Given that the original selling price is 40 yuan and the cost price is 30 yuan, the profit per T-shirt can be expressed as (x + 40 - 30). Also, the sales volume decreases by 10 pieces for every 1 yuan increase in price, so the new sales volume can be represented as (300 - 10x). The total profit, therefore, is given by the product of the profit per T-shirt and the number of T-shirts sold, which leads to the equation: [ (x + 10)(300 - 10x) = 3360 ] Expanding and simplifying this equation: [ 10x(300 - 10x) + 3000 = 3360 ] [ 3000x - 100x^2 + 3000 = 3360 ] [ -10x^2 + 300x + 3000 = 3360 ] [ -10x^2 + 300x - 360 = 0 ] [ -10(x^2 - 30x + 36) = 0 ] [ x^2 - 30x + 36 = 0 ] Solving this quadratic equation, we find two possible values for x: [ x_1 = 2, quad x_2 = 18 ] Since the goal is to reduce inventory as much as possible, we choose the smaller increase in price, x_1 = 2. Therefore, the selling price of the T-shirt should be increased by boxed{2 text{ yuan}}. Part 2: To find the selling price that maximizes profit, we use the profit equation derived from the given conditions: [ M = (x + 10)(300 - 10x) ] [ = -10x^2 + 200x + 3000 ] [ = -10(x^2 - 20x - 300) ] [ = -10(x^2 - 20x + 100) + 4000 ] [ = -10(x - 10)^2 + 4000 ] This equation represents a parabola that opens downwards, indicating that the maximum profit occurs at the vertex of the parabola, which is at x = 10. Substituting x = 10 into the equation for M, we find the maximum profit: [ M_{text{max}} = -10(10 - 10)^2 + 4000 = 4000 ] Thus, the selling price should be set to 40 + 10 = boxed{50 text{ yuan}}, and the maximum profit earned is boxed{4000 text{ yuan}}.

answer:To solve the quadratic equation x^2 + 10x - 24 = 0, we seek factors of -24 whose sum is 10. The pair of numbers that fits this is 12 and -2 (since (12 times -2 = -24) and (12 + (-2) = 10)). Thus, we can factor the quadratic as: [ x^2 + 10x - 24 = (x - 2)(x + 12) = 0 ] Setting each factor equal to zero gives the solutions: [ x - 2 = 0 quad Rightarrow quad x = 2 x + 12 = 0 quad Rightarrow quad x = -12 ] The lesser solution between x = 2 and x = -12 is x = -12, hence the solution to the problem is: [ boxed{-12} ]

answer:The bakery used a total of 0.3 bags of flour, which includes both wheat flour and white flour. We know that 0.1 bag of white flour was used. To find out how many bags of wheat flour were used, we subtract the amount of white flour from the total amount of flour used: Total flour used - White flour used = Wheat flour used 0.3 bags - 0.1 bags = 0.2 bags So, the bakery used boxed{0.2} bags of wheat flour.

answer:The sum of the exterior angles of any polygon is 360°. For a regular polygon, each exterior angle is equal. Therefore, the number of sides of the polygon can be found by dividing 360° by the measure of one exterior angle. Given that one exterior angle is 45°, the number of sides is: [ frac{360°}{45°} = 8 ] Therefore, the correct answer is boxed{text{B}}.