Are all odd numbers prime numbers? Explain.

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).

The ratio of men to women working for a company is 4 to 5 . if there are 90 women working for the company, what is the total number of employees?

Asap! i'm not good math and i'm lost.