I found one that has 45w output, but the output is at 1.5A or 3A with 12V current. Will this charge the minibook x? I bought the laptop this year.
The Charge must be 12V (NEVER use more than the recommended voltage, it would break your machine).
You must have at least* 3A to raise up to 36W (12V X 3.0 A = 36W).
So it will be OK.
*You could use 1.5A, but it would be unefficient. More than 3.0A is OK.