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Explanation:
We'll add up the values in the bottom row of the table.
A value like +150 is the same as simply saying 150
The negatives stick around.
Adding up the values in that row gets us
150 + (-50) + 400 + 300 + (-175) + (-250) = 375
This indicates that over the entire 6 month period, the overall change is +375
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In other words, the initial investment (call it x) has increased by 375 dollars over the 6 month period.
We can then say:
x + 375 = 1500
x = 1500-375
x = 1125
She initially invested $1125
