Answer:
60 words per minute
Step-by-step explanation:
"per" means "divided by" in this context. When you want "words per minute", it means you want the number of words divided by the corresponding number of minutes:
... (900 words)/(15 minutes) = 60 words/minute
-4=2x+16
-16. -16
-20=2x
20/2=2x/2
10=x