Answer:
6.
Step-by-step explanation:
To solve this, you can set up an equation as such:
x²-18= 3x
Now, rearrange this to make it an equation in standard form:
x²-3x-18=0.
Simply turn this equation into factored form:
(x-6)(x+3)= 0.
The only positive solution here is x=6.
