1,076 (the original thickness) - 22.7 meters (loss per year) * 7 (lost 22.7 meters per year for seven years, so multiply the loss per year by the amount of years) = 917.1 (the size after 7 years)
A.K.A 1,076 - 22.7 * 7 = 917.1
i found this off of the internet so im sorry if its wrong