52/7 fraction form plz is for my homework

What is the measure of ac? 5 units 13 units 26 units 39 units

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).

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?