Jenn and David shared a candy bar. Jenn ate three tenths. David ate four tenths. How much is left?
Jenn ate 3/10 of the candy bar and David ate 4/10 of the candy bar.
The total amount they ate is 3/10 + 4/10 = 7/10 of the candy bar.
Therefore, 1 - 7/10 = (10/10) - (7/10) = 3/10 of the candy bar is left.