Growth Rate 的計算

Growth rate = (New - Old) / Old x 100%

Example:

B company's profit in 2009 = $10m, 2008 = $1m
Growth rate = 900% (dollar amount growth = $9m)

C company's profit in 2009 = $7m, 2008 = -$2m (loss)
Growth rate = ?? (dollar amount growth = $9m)

What is C company growth rate?