Answer:
$150 million
Explanation:
The reserve requirement is the amount of money required by the Fed for banks to keep as reserves.
If the reserve ratio is 25%, when the Fed buys securities of 200 million, the reserve would be 0.25 x 200 =$50 million
The amount that would be available for lending would be ($200 - $50) million = $150 million
Money supply would increase by a maximum of $150 million
I hope my answer helps you.