This one's tough because based on the wording there are a few different ways to construct the formula. Initially, I constructed the formula as .01*20,000+600(n-1)= 2,000

Then I compared it to

200+400+800+1600=3,000

Neither of these are answers. So in going back to the problem, I realized that each month the late either doubles or is an additional 600. I thought it was an either/or calculation.

Then I calculated the incremental penalty for each month and compared to see if it exceeded $600.

200+200+400+600=1400.

1st month late) .01*20,000=200

2nd month late) An additional 200 which is less than 600, total owed after one month 200+200=400

3rd month late) An additional 400 which is less than 600, 400+400=800

4th month late) An additional 600 since, double the penalty would be 800 which exceeds 600. So it's 800+600=1400, A.

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I'd love to hear any feedback or ways to improve my problem solving. I make a lot of silly mistakes. If you've had luck improving on stupid mistakes, I'd love to hear how you did it.

Also, I appreciate any kudos.