Another basis questions I'm having trouble with:

Find basis for the following subsbace of R^5:

W1 = {(a1,a2,a3,a4,a5) which is an element of R^5: a1-a3-a4=0}

and

W2 = {(a1,a2,a3,a4,a5) which is an element of R^5: a2=a3=a4 and a1+a5=0}

What are the dimensions of W1 and W2?

Thanks in advance.