Given:
The restaurant already has 448 ounces
And then buys 20 pounds
The next step is to ensure that they are both in the same units
To do this we will have to convert pounds to ounces
The conversion rate is given by
1 pound = 16 ounces
So we will have to convert 20 pounds to ounces
20 pounds = 16 x 20 ounces = 320 ounces
Then we can add 320 ounces to the initial 448 ounces
The correct option is 768 ounces which correspond to option A