A(t) = 1600(1.0125)^(4t)
A(1) = 1600(1.0125)^(4*1)
A(1) = 1681.5125390625
A(1) = 1681.51
After 1 year, you'll have $1681.51 in the account.
A(t) = 1600(1.0125)^(4t)
A(5) = 1600(1.0125)^(4*5)
A(5) = 2051.25957073373
A(5) = 2051.26
After 5 years, you'll have $2051.26 in the account.
Then,

Interpretation: you earn about $92.44 per year over the period from year 1 to year 5.
This is the average rate of change (aka slope). The A(5)-A(1) in the numerator represents the "rise", and the "5-1" in the denominator is the "run".