Answer:
It was 4 years.
Explanation:
To solve this problem we need to use the appropriate formula for simple interest, which is shown below:
M = C*r*t
Where M is the amount of interest, C is the initial amount of money, r is the rate of interest and t is the time elapsed in years. Applying the data from the problem we have:
840 =7000*0.03*t
840 = 210*t
210*t = 840
t = 840/210
t = 4
It was 4 years.