#### Answer

11$r^{3}$+11

#### Work Step by Step

STEP 1: First, write down the equation.
(5$r^{3}$ + 8) + (6$r^{3}$ + 3)
STEP 2: In order to add binomials, we combine like terms. First, group the like terms together.
(5$r^{3}$ + 6$r^{3}$) + (8 + 3)
STEP 3: Then, add the coefficients together to simplify.
(11$r^{3}$) + (11)
11$r^{3}$ + 11