You have to move your variables around.<span />
I’m not sure abt 21 but 22 is the second one and the 4th one. So 2,4.
Answer:
10.14 years
Step-by-step explanation:
The following equation describes the percentage of all eligible voters that are registered to vote as a function of time:
V=100-30e^{-0.04t}
The time 't' for which V(t) = 80 is the amount of years required for the percentage of registered voters to reach 80%:
80=100-30e^{-0.04t}\\\frac{20}{30}= e^{-0.04t}\\ln(\frac{2}{3})=-0.04t*ln(e)\\ t=10.14\ years
It will take 10.14 years until 80% of all eligible voters in your county are registered to vote