You can work out the difference between the numbers by taking the smaller one away from the larger one:
70.20 - 65 = 5.20
Then you can divide the difference (5.20) by the original number (65) to get how many percent it is of 65 in decimal form:
5.20/65 = 0.08
Then you can times it by 100, to get the percentage:
0.08 * 100 = 8%
This means there was a 8% price increase in $65 to get to $70.20
Hope this helps! :)