Someone please explain

Evaluate 8j -k+148j−k+14 when j=0.25j=0.25 and k=1k=1.

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

What’s the answer? and how do i solve it ?