The distance across a sink drain is 3.8cm….. is it a diameter

Find the gradient of f(x,y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

Me with this one question, and i'll upvote the brainliest answer

9/10 divide by -3/15 as a mixed number