Hi everyone , can anyone of you help me with this question ?

My background in Algebra is weak

Thanks a lot guys

Let T : V -> W be a linear mapping and let {v1, v2, ..., vn} be a basis for V such that {vr+1,...,vn} is a basis for Null(T). Prove that {T(v1),...,T(vr) is a basis for the range of T.

clear explanation is appreciated.