If he types 36 words in 2/3 of a minute, we first need to find out what his speed is in 1/3 of a minute.
To do this, we divide 36 by 2 which gives us 18.
So if Yousef can type 18 words in 1/3 of a minute, we multiply 18 by 3 to work out how many words he types per minute.
18 x 3 = 54
Therefore Yousef types 54 words per minute.
Another method:
Another method to do this would be to take the 36 and divide it by 2/3 which would give us 54.