Which what is the algebraic expression for nine less dense some number

100 points, hi, i’m not sure what to do here,the data doesn’t seem to be quadratic .? can anyone me, in advance

Empty box + box + empty box fill in the box is equal to 30 how

The figure below shows rectangle abcd and the triangle eca on a coordinate plane.which of the following expressions represents the perimeter of triangle of triangle eca in units