In a factory where mint and lemon candies are produced, candies are packaged with 10 pieces in each package. These packages contain only mint candies, only lemon candies, or equal numbers of mint and lemon candies.
In this factory, a total of 1200 candies were produced and packaged, of which 400 were lemon.
If the total number of packages containing only one type of candy is 70, how many packages contain only mint candies?
A) 40
B) 45
C) 50
D) 55
E) 60