One wall of Allysa's room is 3 m long. She is making a ceiling border for that wall by pasting \( \frac{3}{10} \mathrm{~m} \) pieces of wallpaper trim end-to-end. So far she has pasted 9 pieces of trim. How long does she have to make the last piece of trim to complete the project?

Allysa's wall is 3 meters long, and so far she has pasted 9 pieces of trim, each measuring \( \frac{3}{10} \) m. To find out how much trim she has already pasted, we multiply the number of pieces (9) by the length of each piece: \( 9 \times \frac{3}{10} = \frac{27}{10} = 2.7 \) m. Now, we subtract this length from the total wall length: \( 3 - 2.7 = 0.3 \) m. So, Allysa needs to make one last piece of trim that is \( 0.3 \) m long to complete the project! If Allysa wants to ensure everything fits perfectly, she could measure the space again before cutting. It's often the little things that can cause the most hassle, like ensuring each piece is cut straight. And remember, even if you're measuring twice, it never hurts to double-check your calculations for that perfect finish!