3 factories manufacture hubcaps. 2 of the factories can each produce 100,000 hubcaps in 15 days. The third factory canproduce hubcaps 30% faster. About how many days would it take to produce a million hubcaps with all these factories working simultaneoously?

The book gives this as the solution: two factories make 100,000/15 = 6,667 per day. The third makes 1.3 x 6,667 = 8,667. 8,667 +2[6,667] =22,001 hubcaps per day. It would take 45.5 days to produce a million hubcaps.

My question is where did they get 1.3?