9.20: First, the area of the triangle is $\dfrac{\sqrt{2}R\cdot\sqrt{2}R}{2}$.  Then you should have the right answer.  Note that the question says using the approximation $\dfrac{22}{7}$ to represent $\pi$, and write the ratio in the form of $\dfrac{P}{Q}$, and then the final answer is $P+Q$.

9.24: When a straight line is tangent to a circle, it is always useful to connect the center and the tangent point.  This is the radius that is perpendicular to the tangent line.  In this problem, look at one of the six circles that touch the rubber band, and connect its center with the two tangent points.  What angle do these radii form?  Also, look at the straight line segment that is tangent to two of the circles.  After connecting the two radii that are perpendicular to the segment, and connecting the two circle's centers, you are getting a rectangle.  What is the length of this straight segment?

9.28: This problem is not really a hard one.  You need to trace the original point A, and each time the rectangle rolls 90 degrees, the point will either go through a quarter circle path (if it's not the center of rotation), or simply stay put (in the case that it is the center of rotation).  So just carefully trace the path, and calculate the quarter circles, and add them up.