3/5mixture = sauce
2/5mixture = 240g meat

5/5 mixture = 600g (total)
3/5 mixture = 360g sauce

After added more meat
9/20 = 360g sauce
20/20 = 800g (new total)

800-600 = 200g (more meat added)

the answer key stated that it’s 440g

200g new meat + 240g initial meat = 440g