Answer: $3865.8
Step-by-step explanation:
The formula to find the simple interest is given by :-
, where P is the initial amount deposited , r is the rate of interest in decimal and t is the time period in years.
Given : P= $1700 ; r= 9.8%=0.098 ; t=13 years
Then , the simple interest earned in 13 years will be :-

Now, the combined amount = P+I =$1700+$2165.8= $3865.8
Hence, the credit union would owe Heather $3865.8 in 13 years.