In summary: You now have a good understanding of the problem. Just keep practicing problems like this and it will become second nature. Keep up the good work!In summary, the maximum angle at which the box will not slide back down is when the tangent of the angle equals 0.7, which is found by setting the sum of forces in the x direction to equal 0 and using trigonometric functions to solve for the angle. It is important to accurately set up the equations and consider the direction of forces in order to find the correct answer. Practice and understanding of these concepts will make solving physics problems easier in the future.