As shown in the figures given :
For Figure 1 : perimeter = 8 units [As can be seen in the figure]
For figure 2(with 2 octagons) : perimeter = 8 × 2 - 1 = 15 units [since 1 side is common ]
For figure 2(with 3 octagons) : perimeter = 8 × 3 - 2 = 22 units [since 2 sides is common ]
If one more octagon is added
then perimeter = 8 × 4 - 3 = 29 units [since 3 sides will be common ]
If you add up 57+23=80 40+40=80 so 40 is the answer they will have the same amount Alice gets 40 and her sister gets 40
There isn't any choices given in this problem but I can give you a tip to answer these kinds of problem. When you say independent, it means that the equation cannot be algebraically altered to result to 3x + 4y = 8. So the equation 6x + 8y = 16 is not an independent equation since when you divide each side by 2 it will result to 3x + 4y =8. You get the idea. <span />