Let's build the equation counting how many x's and 1's are there on each side.
On the left hand side we have 5x's and 8 1's, for a total of
On the left hand side we have 3x's and 10 1's, for a total of
So, the equation we want to solve is
Subtract 3x from both sides:
Subtract 8 from both sides:
Divide both sides by 2:
To answer this question we can propose the following equation:
Where:
x is the number of weeks elapsed.
d is the debt depending on the weeks.
Robert promised to pay at least $ 67 each week.
Therefore, after 5 weeks the debt of rober should be:
Then scenario A) is possible because .
After 6 weeks:
Then scenario B) is possible because .
After 7 weeks
Then scenario C) is possible because .
After 8 weeks
So scenario D) is NOT possible because
Finally the correct answer is option D.