Question

Two hundred minus three times a number is equal to nine.

Answer 1

I assume you want to know "the number"?

we can write down what you said like this:

200-3x=9

where x is the number.


200-3x=9//moving variables to the left, rest to the right
-3x=9-200//multiply by-1
3x=191//divide by 3
x=63 $\frac{2}{3}$

and that is the answer