Two typers can type a book together in 4 days. How many days will it take each of them to type the book alone if the first one types twice as fast as the second one?

Therefore, the first finished the book alone for the 6 days.

Therefore, the second finished the book alone, for the 12 days.

Step-by-step explanation:

We have that is the first one types twice as fast as the second one.

The first = 2/3

The second = 1/3

For first case we have the following proportion:

2/3 : 4=1 : x

x · 2/3 = 4

x=6

Therefore, the first finished the book alone for the 6 days.

For second case we have the following proportion:

1/3 : 4=1 : x

x · 1/3 = 4

x=12

Therefore, the second finished the book alone, for the 12 days.