Sorry, I don't get the problem that well. Here is my best shot at it:
There are 18 years and 12 months in each year. In order to calculate the amount warned per month, we will have to compute: \((75000/18)/12 \implies 9875/27\)
After doing this, set x as the amount that has to be paid: \(.039x=9875/27\)
Then just compute:\(x=9377.9677113\)
Note: Electric Pavlov's answer is far more likely to be correct, so if ours are different, go with his/her's
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