Lee had a total of 40 e-mails on Monday. Eight of the e-mails were from her friend Cara. What percent of the e-mails were from Cara?

8/40=x%

x%=x/100

8/40=x/100

1/5=x/100

100=5x

divide both sides by 5

20=x

answer is 20%

To find the percent of the e-mails from Cara, divide the number of the emails which are from her by the total number of emails and multiply the quotient by 100%. This is shown below,

(8 / 40) x 100% = 20%

Thus, 20% of the emails are from Cara.