Answer: 7
Step-by-step explanation:

Let <em>f(x)</em> be the sum of the geometric series,

for |<em>x</em>| < 1. Then taking the derivative gives the desired sum,

Answer:
Step-by-step explanation:
You would do 21,000×0.20, which equals 4,200. Since 4,200 equals 20% of 21,000, then you would do 21,000-4,200, which equals 16,800. So the car is worth $16,800 dollars this year.
4/5 = 0.80
1/5 + 3/5 = 3/5 + 1/5