We're going to use the compounded intrest formula:

Where P is the initial cost
r is the rate as a decimal
n is the amount per year that you invest the rate
t is the amount of time at which you're checking how much it's worth (yrs)
Using this information, we can use:

So your answer will be
B.
Answer:
x=4
Step-by-step explanation:
If 200 grams stretches the spring by 5 cm that means 100 grams stretches it by 2.5 so 20 - 2.5 = 17.5 cm is the unstretched length of spring, hope I helped