Since the angles in a triangle adds up to 180, and A is 40 degrees, B and C have a total of 180-60 = <<180-60=120>>120 degrees.
Since B is two times bigger than C, the total of the angles of B and C is equal to 2C+C = 120
3C=120
The angle of C is C=120/3
C is <<40=40>>40
Since B is two times as big as C, B is 2*40 = 80 degrees.
#### 80