projectile

An ion’s position vector is initially 𝑟⃗ = 5 𝑖̂− 6𝑗̂+ 2 𝑘̂ , and 10 s later it is 𝑟⃗ =
−2 𝑖̂+ 8𝑗̂− 2 𝑘̂ , all in meters. In unitvector notation, what is its 𝑣⃗𝑎𝑣𝑔 during the 10 s?