Formula is

D represents the amount of a regular deposit
r represents the annual interest rate
m is the number of equal compounding period
t the time in years,
F is the future value
D = 100, r= 0.85%= 0.0085, m= 1 and t=10
m*t= 1*10 = 10
Plug in all the values in the formula

= 1039.13
Karen opens a savings account with $1500
Already he has 1500
So account balance = 1500 + 1039.13 = $2539.13