9= -5g -23 i don't understand how to do this and i'm trying to my son

With all due respect, your parental instinct is inspiring, but if you
don't understand how to do it, then you cannot help your son.

Here is a procedure that will lead to the solution ... the one value
of  'g'  that makes the equation a true statement:

1).  Add  23  to each side of the equation.

2).  Divide each side of the equation by  5 .

3).  Multiply each side by  -1 .

1. 9 = -5g -23
2. 9 + 23 = -5g
3. 32 = -5g
4. -32/5 = g