If John can paint a room in 6 hours and Bill can paint the same room in 9 hours, how long will it take them working together to
paint the same room?

The first week samantha learned to read braille, she could read 10 words per minute. in the second week she increased her speed by 20%. in the third week she increased her speed again by another 25%. how many words could she read per minute by the third week? hurry and tell me!