Answer:
16.4
Explanation:
To decrease a number by 45% of its value, you subtract the 45%. To get 45%, you multiply the number by 0.45.
So, if x is the original number, then the equation for this word problem would be x - 0.45x = 9.
To solve, we first subtract 0.45x from x, which is 0.55x. This means that 0.55x is equal to 9. To simplify, we can divide both sides by 0.55. 9/0.55 is 16.36363636..., etc. The nearest tenth would be 0.4, so your answer is 16.4