2-3.1/7(2-1.9/11):8/21

Question

2-3.1/7(2-1.9/11):8/21

Comments

=1/2

---

cпс знаю

Answer 1

2-1 9/11=2/11
3 1/7×2/11=22/7×2/11=4/7
4/7÷8/21=4/7×21/8=3/2=1 1/2
2-1 1/2=1/2