giúp em với mng oiiiii

`2)`

\(\%^{10}B=x\%\)

\(\%^{11}B=(100-x)\%\)

`->A_B={10x+11(100-x)}/{100}=10,81`

`->x=19`

Vậy \(\%^{10}B=19\%;\%^{11}B=81\%\)

`3)`

`A_{Cl}={35.75+37.25}/{100}=35,5(u)`

`4)`

\(\%^{63}Cu=x\%\)

\(\%^{64}Cu=(100-x)\%\)

`->A_{Cu}={63x+64(100-x)}/{100}=63,54`

`->x=46`

Vậy \(\%^{63}Cu=46\%;\%^{64}Cu=54\%\)

`5)`

`A_{Ni}={58.67+60.26+61.7}/{100}=58,73(u)`