Answer:

n=  −9x2−25 /3x

Step-by-step explanation:

Let's solve for n.

9x2+3nx+25=0

Step 1: Add -9x^2 to both sides.

3nx+9x2+25+−9x2=0+−9x2

3nx+25=−9x2

Step 2: Add -25 to both sides.

3nx+25+−25=−9x2+−25

3nx=−9x2−25

Step 3: Divide both sides by 3x.

3nx /3x  =  −9x2−25 /3x

n=  −9x2−25 /3x