Final answer:
To determine the number you will write down (x) after taking 7 away from your original number and multiplying by 10, you can use the formula x = (n - 7) x 10.
Step-by-step explanation:
To determine the number you will write down (x) after taking 7 away from your original number and multiplying by 10, you can use the formula x = (n - 7) x 10, where 'n' represents the number you are thinking of.
For example, if you are thinking of the number 10, the formula would be x = (10 - 7) x 10, which simplifies to x = 3 x 10, resulting in x = 30.