Question

After reading 80% of her emails in her inbox, Danette still has M unread emails.

Answer 1

Answer:

$\frac{M}{1-0.8}$ and $5M$

Step-by-step explanation:

1. Let's imagine that you have 100 e-mails unread. When you read 80% of these e-mails you have the following amount $M$ unread:

$100-(0.8)(100)=20$ e-mails

2. If you substitute 20 e-mails into the equations shown above, you will obtain the original amount:

$\frac{20}{1-0.8}=100\\5(20)=100$

Answer 2

answer :  option A  and B

After reading 80% of her emails in her inbox, Danette still has M unread emails

M unread emails

Let x be the number of emails before reading

80% of emails are left in the box. So, 0.08x  emails are left in the box

Now we make an equation

number of emails - 80% of unread emails= number of unread mails

x  - 0.08x = M

Now we factor out x

x ( 1- 0.08) = M

So $x = \frac{M}{1-0.8}$

or $x = \frac{M}{0.2}= 5M$