Question

.

Answer 1

is this calculus ? (or are you supposed to use calculus to answer it?)

Answer 2

if we have P of something, and it grows 10% in one year we would write an equation that looks like this
\[ y = P + 10\% \cdot P \]
or , changing 10% to 0.1
\[ y= P+0.1P \\ y= (1+0.1)P \]
if it grows another 10% the next year, we would write
\[ y= ( (1+0.1)P ) \cdot (1+0.1) \\
y= (1+0.1)^2P \]
in in n years
\[ y= (1+0.1)^nP \]

Answer 3

notice that 10% growth means (1.1)^x

if we had 0.9 instead of 1.1, instead of growing, P would get smaller
\[ y = 0.9P = (1 - 0.1)P = P - 0.1P = P - 10\% P \]
0.9 means it decreases by 10% each year.

Answer 4

For your problem, I would change 0.82 to 1 + some number
then change the "some number" to a percent