Change this Mixed number into a improper fractions: 3 and 6/8

It takes evan 6 3/4 to mow 3 lawns. it takes 2 1/3 hours to mow me. gals lawn and 1 3/4 hot mow ms. lee’s lawn. how many hours does it take evan to mow the third lawn?

Find the balance at the end of 4 years if 1000 is deposited at the rate of

Pls! does anybody know a shortcut for answering these types of questions in the future?