Find the rate of change and the initial value for both group n individual session

All you have to do to solve this is subtract the first value in a row from the second value in that row, for example $69 - $39.5. That's the rate of change. If you want to check your work, you could subtract the second from the third or the third from the fourth etc. to see if they match. To find the initial value, just subtract the rate of change from the first-hour value.