Answer:
209,000
Step-by-step explanation:
(500+200=700)
(700*300=210000)
210000-1000=209,000
10+6=16
7+9=16
Therefore, the mystery number is 9.
If there are multiple operations at the same level on the order of operations off from left to right and you work like this first noticed that there are no parentheses or exponents so we moved to multiplication and division with any sense of parentheses