28 because a constant is a number that doesn't have x attached to it.hope this helps
sqrt 7 ( sqrt 14 + sqrt 3 )
distribute
sqrt(7) sqrt(14) +sqrt(7) *sqrt(3)
sqrt(98) + sqrt(21)
sqrt(49*2) + sqrt(21)
sqrt(49) * sqrt(2) + sqrt(21)
7sqrt(2) + sqrt(21)
D because coefficient is the number next to the variable and 7 is the coefficient to the fifth power