Response:
The interest rate is 5.7% $21.204
Clarification:
The formula for calculating simple interest is
I =

Given that
I = Interest, T = time;;R is rate; P = principal
John earned this interest by July 1, 1993 as follows:
I =
= 72
Consequently, the total amount in John's account by July 1, 1993 would then be
= $300 + $72= $372
This indicates he utilized these funds at an interest rate of q.
On July 1, 1998, John’s total was $520, meaning the interest accumulated in these five years equals $520 - $372 = $148.
Using the simple interest formula: Interest = PRT/100
148 =
= 14,800 =2600q
q =
Thus, the rate is found to be 5.7%
The interest amount between July 1, 1993, and July 1, 1994 calculates as
I = 
= $21.204