Wilson paints 40% of a bookcase in 20 minutes how much more time will it take him to finish the bookcase?

30 minutes

Step-by-step explanation:

He paints 40% of the bookcase in 20 minutes.

The rest of the bookcase is 100% - 40% = 60%.

60% of the bookcase still needs painting.

40% is to 20 minutes as 60% is to x minutes

40/20 = 60/x

Reduce the fraction on the left side.

2 = 60/x

Multiply both sides by x.

2x = 60

Divide both sides by 2.

x = 30

30 minutes