Answer:
[x + (9 - 1) 25] = 300
$100
Step-by-step explanation:
Hallie's mother gave her a birthday check of $x to start a savings account.
She also plans to save $25 per month as well.
So, after 9 months Hallie has in her account $[x + (9 - 1) 25]
Therefore, from the given condition we can write that
[x + (9 - 1) 25] = 300 ......... (1) (Answer)
⇒ x + 200 = 300
⇒ x = $100
So, the original check amount from Hallie's mother was $100. (Answer)