Can anybody solve this for me please?

After reading 80% of her e-mails in her inbox, danette still has m unread e-mails. which of the following expressions could represent the number of e-mails danette had in her inbox before she started reading? choose 2 answers: (choice a) 5m (choice b) 1.8m (choice c) 80m (choice d) m/0.8 (choice e) m/1−0.8

Roderick wants to draw a circle for which the numerical value of the circumference is greater than the value of the area.which lengths could he use for the radius? check all that apply

Maria heard on the radio that the high temperature that day would be to determine the temperature in degrees celsius, she used the formula , where c is the temperature in degrees celsius and f is the temperature in degrees fahrenheit.