2. In both cases, if the width is x, the length is 2x. The first type: if the length of the wall is rectangular, then x+x+2x=24, x=6, 2x= 12, and the area is 6× 12=72 square meters;

Second, if the width of the wall is rectangular, then 2x+2x+x=24, x=24/5, 2x=48/5, and the area is 24/5 * 48/5 =1152/25.

3. If the distance traveled is x, then the whole journey is 3x. If x+ 15=3/2x, then x=30, and the whole journey is 3x = 3× 30 = 90km.