Simplify the Algebraic Expression $$- 5 x ^ { 7 } + 8 x ^ { 7 }$$

Simplify the algebraic expression.
- $$- 5 x ^ { 7 } + 8 x ^ { 7 }$$

A) $3 x ^ { 7 }$
B) $2 x ^ { 7 }$
C) $3 x ^ { 49 }$
D) $3 x ^{14}$