Question

After reading 80\%80%80, percent of her e-mails in her inbox, Danette still has MMM unread e-mails.

Answer 1

The required expression is
`x= (M)/((1 - 0.8))` or
`x=5M`

Explanation:

Consider provided information.

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

Now we need to determine the expression, that could represents the number of emails Danette had in her inbox before started reading.

Let x be the number of emails before reading.

She reads 80% of x

80% can be written as 0.08.

Therefore,
`0.80x` is the number of mails she read.

Thus, the unread e-mails are

`x - 0.8x = M`

Now we factor out x

`x(1 - 0.8) = M`

`x=(M)/((1 - 0.8))`

`x=(M)/(0.2)`

`x=5M`

Hence, the required expression is
`x= (M)/((1 - 0.8))` or
`x=5M`