Can someone please do this question as example,thanks

Question

Idk what the l symbol is called, it makes everything positive
1) r and s are two vectors and l r l = 5
Find the value of l r + s l when:
a) s = 5r
b) s = -2r
c) r is perpendicular to s and l s l = 5
d) s is perpendicular to (r + s) and l s l =3

Answer 1

if s is a multiple of r, then just add the magnitudes.
If r⊥s then r+s is just the diagonal of the rectangle formed by r and s

If s⊥(r+s) then s•(r+s) = 0
so what does that mean?