What is four sevenths plus eight thirteenth?

To add four sevenths and eight thirteenths, we first need a common denominator. The least common multiple of 7 and 13 is 91. Converting the fractions, we get ( \frac{4}{7} = \frac{52}{91} ) and ( \frac{8}{13} = \frac{56}{91} ). Adding these gives ( \frac{52 + 56}{91} = \frac{108}{91} ), which can be simplified to ( 1 \frac{17}{91} ).