I think it might take 4/6, or 2/3
Explanation: because 1/2 a can of sauce covers 3/4 of the pizza, you still need 1/4 of the pizza covered. 1/4 if 1/3 of 3/4. That means you need an additional 1/3 of the 1/2 can of sauce - 1/3 of 1/2 is 1/6. So, if we add the original 1/2, which is equal to 3/6, with the additional 1/6, we get 4/6. 4/6 can be simplified to 2/3. I’m not sure if I’m right cause I’m bad at math but you could give it a try. :)