Bases for a subspace and its orthogonal complement

Let V⊂R5 be the subspace defined by the equation

x1−2x2+3x3−4x4+5x5=0.

(a) Find (with justification) a basis for V.
(b) Find (with justification) a basis for V⊥, the subspace of R5 orthogonal to V under the usual dot product.