Answer:
Sonja invested for 5 years.
Step-by-step explanation:
First you have to find how much money she gets in one year.
To do this you would have to multiply 15,000 and 2.8.
15,000 x 2.8 = 42000
You move the decimal 2 spaces forward since there are 3 zeros in 15,000 and one decimal place in 2.8.
This gives you 420.
To find how many years it takes for her to make $2100 you have to divide
2,100/420.
This gives you 5, which means that she invested for 5 years.
