I will rewrite the wording and write out the equation as it goes so there is better understanding. Once I do that, I will solve it for you.
Nine times a number (9n) is (=) one more than ten times the number (10n + 1).
Now that we've rewritten it, let's only write what we have in parenthesis.
9n = 10n + 1.
Now that we have our equation, let's solve!
9n = 10n + 1
Subtract 10n from both sides.
-1n = 1
Divide both sides by -1.
n = -1
I hope this helps!