A plant grows at a constant rate after being planted at a certain initial height. The relationship between the total height of the plant, $P$, in centimeters, and the number of days it has grown, $g$, is represented by the equation $P-1.2g=10$. If the plant grows at a rate of 1.2 centimeters per day, what was the initial height of the plant, in centimeters, when it was planted?