Answer:
Total amount of money that jane has will be $8674.576 
Explanation:
Given data:
Time duration from 9 april to 20th august
so total number of days is = 21 ( of april) + 31 +30 +31 +20 ( august) = 123
We know that, 
simple interest is given as

where, P is principle = 8400
T = time = 123 ÷ 365
R = Rate = 9.2
so we have Simple Interest 

simple interest = $274.576 
Total amount of money that jane has will be 
 = 274.576 + 8400 = $8674.576