Question

After reading 80% of her e-mails in her inbox, Danette still has M unread emails. Which of the following expressions could represent the number of e-mails Danette had in her inbox before she started reading?

Answer 1

Answer:

m/(1 - .8)

Step-by-step explanation:

She read 80% of her emails, which is .8 of the total.  So her unread emails would be 100% - 80% = 1 - .8

that means me can be written as:

m = (1 - .8)t

where t is the total

If we solve for t, we get:

t = m/(1 - .8)

Answer 2

Answer with explanation:

Let number of emails in Danette inbox before she started Reading= x

Number of emails Read =80% of the email

Number of emails left after reading 80% of the emails =M

  A.T.Q

$\rightarrow x-\frac{80x}{100}=M\\\\\rightarrow \frac{100x-80x}{100}=M\\\\\rightarrow \frac{20x}{100}=M\\\\ \rightarrow x=\frac{100M}{20}\\\\x=5 M$

Number of emails in Danette inbox before she started Reading =5 M