Answer:
900pages=45minutes
Explanation:
Step 1: Find the unit rate=how many pages he can type in 1 minute
to find the unit rate,
k=y/x
y=400 pages
x=20 min
400/20=20 pages in 1 minute
Step 2: Multiply the amount of pages by 45
k times x = y
20 times 45= 900 pages in 45 minutes
So, it will take the secretary 45 minutes to type 900 pages.