Answer:
24 inches represents 9 miles in the map
Step-by-step explanation:
To solve this problem you take into account that 8 inches represents 3 miles and that x represent the number of inches for 9 miles. That is:
8 ------- 3
x ------- 9
This is simply a rule of three, then you calculate:

Hence, 24 inches represents 9 miles in the map
Based on the numbers we have we can assume that she saves 3 times more each week than the last (1*3=3, 3*3=9).
Following this trend we would multiply the amount she saved the third week ($9) by 3 to get $27 for the fourth week.
Then, we would multiply the amount she saved the fourth week ($27) by 3 to get $81 for the fifth week.
Finally, to figure out how much she saved in the 5 weeks, we need to add each value up to get 1+3+9+27+81= $121 saved in 5 weeks
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