Find the value of c that completes the square x^2-6x+c

please help me with the math problem and show me how to do these kinds.

Thank you.

The answer is 9

Step-by-step explanation:

for the equation:

move the -6x

x^2 + c - 6x

To find c :

c = (b/2)^2

this means you have to divide the coefficient of x by 2 then square the result

If you dont understand I put a picture of all the steps

the monthly balance will be $75,000

x/3-10=8

x/3=18

x=48