position vectors and displacement?

Question

A positron undergoes a displacement (delta) r = 8.0i - 2.0j + 6.0k, ending with the position vector r = 9.0j - 2.0k, in meters. What was the positron's former position vector?

Answer 1

Δr = rf - ri

(8, -2, 6) = (0, 9, -2) - ri

(8, -2, 6) - (0, 9, -2) = -ri

(0, 9, -2) - (8, -2, 6) = ri

(-8, 11, -8) = ri