Making a knife-cut steamed bun has 8 grams more flour than making a meat steamed bun.

Making 12 knife-cut steamed bread has more flour than making 12 meat steamed buns, with 8x 12=96 (g).

This bag of flour is just enough to make 12 knife-cut buns, and if it is all made into meat buns, it is just enough to make 15.

So 96 grams can make 15- 12=3 steamed buns, and each steamed bun needs flour: 96÷( 15- 12)=32 (grams);

Each steamed bread needs: 32+8=40 (g)

1, if you make 15, how many grams of flour do you still need?

40x( 15- 12)= 120(g)；

2. If you make 12 meat buns, how many grams of flour are left?

Making 12 knife-cut steamed bread has more flour than making 12 meat steamed buns, with 8x 12=96 (g).

So there are 96 grams of flour left.