2-Bromobutane reacts with $\mathrm{NaOEt}$ in ethanol by E2 to give only but-2-ene (cis + trans together) and but-1-ene. Treat each hydrogen separately: every H on C-3 leads to but-2-ene and is 4.0 times as reactive as every H on C-1, which leads to but-1-ene. Now the deuterated substrate $\mathrm{CH}{}_3-\mathrm{CHBr}-\mathrm{CD}{}_2-\mathrm{CH}{}_3$ is used; each D on C-3 is removed 6.0 times more slowly than the corresponding H ($k_H/k_D=6.0$) and all other factors are unchanged. What is the percentage of but-2-ene in the alkene product from the deuterated substrate? Give the answer to the nearest integer.

Numerical answer type, tolerance 0.5.