Answer:
Coin A :

Coin B :
Explanation:
Consider the given formula is
where, P is current value, V(t) is the value of the coin in t years, and r is annual appreciation rate.
For coin A, current value is 25 dollars and annual appreciation rate is 7%.
For coin B, current value is 40 dollars and annual appreciation rate is 5%.
Therefore, the required equations for coin A and B are
and
respectively.