a-->It'll take Diego 11 minutes to type 385 words.
b-->Diego can type 525 words in 15 minutes.
To find the answer to a and b, first you have to find how many words Diego can type in 1 minute. To do that, divide the amount of words he can type (140) by the minutes (4).
140/4 = 35
That means Diego can type 35 words per minute.
For a, divide 385 by 35.
385/35 = 11
It'll take Diego 11 minutes to type 385 words.
For b, multiply 35 by 15.
35*15= 525.
Diego can type 525 words in 15 minutes.
Hope this helps!
Let me know if you need anything else :)