Answer: Jessica ate 3/10 of the pizza
Explanation:
We know that combined, Lulu and Jessica ate 7/10 of a pizza. Since we are given that Lulu at 4/10 of the pizza, we subtract 4/10 from 7/10. Because the denominators are the same, we can easily subtract without any extra step. 7/10 - 4/10 = 3/10