To calculate the percent of change, we can use the following formula:
Percent of change = (final value - initial value) / initial value x 100%
In this case, the initial value is $15 and the final value is $100. Plugging these values into the formula, we get:
Percent of change = ($100 - $15) / $15 x 100% = 567%
So the percent of change in Ron's savings account balance is 567%. This means that Ron's balance increased by 567% from its initial value of $15 to its final value of $100.