Answer: 139 copies of her book were sold.
Step-by-step explanation:
Hi, to answer this question we have to analyze the information given:
Earnings (d)
Where "n" is the number of copies sold.
If she earned $22,100, we have to replace the value of d by the number given:
22,100 = 20,009 +0.15 n
Solving for n
22,100-20,009 = 0.15n
2,091=0.15n
2,091/15=n
139.4=n
n≅139 books (rounded)
Feel free to ask for more if needed or if you did not understand something.