Question

[Mori Ran]

cho A = 1+ 2 + 3 + 4 + ..... + 19

             11 + 12 + 13 + ..... + 29

a, rut gon A

b, xoa 1 so hang o tu, 1 so hang o mau de co 1 phan so bang phan so da cho

Answer 1

[Thao Nhi]

\(A=\frac{\frac{\left(19+1\right).19}{2}}{\frac{\left(29+11\right).19}{2}}=\frac{190}{380}=\frac{1}{2}\)