Find the torque of a corce `7hati-3hatj-5hatk` about the origin which acts on a particle whose position vector is `hati+hatj-hatk`
Given: `vecF=7hati-3hatj-5hatk`

Explanation

`vec tau= vecr xx vecF|{:(hati, hatj, hatk),(1,1,-1),(7,-3,-5):}|`