Suppose that a nation currently is producing combination B in the table below and on the graph of the production possibilities curve to the right. What is the opportunity cost of producing 2.0 million more smartphones and moving to production combination

A?

Combination	Smartphones (millions per year)	Tablets (millions per year)
A	50.0	0
B	48.0	10
C	45.0	20
D	40.0	30
E	33.0	40
F	22.5	50
G	0.0	60

The opportunity cost of producing 2.0 million more smartphones and moving from production combination B to production combination A is _____ million tablet devices per year. (Enter your response as a whole number.)