Volume of a rectangular box is
[tex]v=\text{lbh}[/tex]for B1, the ratio is 5:2:1
For B2, the ratio is 6:2:1
Given,
2x=2x
x=2
thus,
the volume of B1 is
[tex]10\times4\times2=80[/tex]the volume of B2 is
[tex]12\times4\times2=96[/tex]Thus the ratio is
[tex]\frac{80}{96}=\frac{5}{6}[/tex]