hello
from the question given, we have
[tex]\begin{gathered} 86\text{chairs}=2\text{rows} \\ x\text{ chairs= 1 row} \end{gathered}[/tex]cross multiply both sides
[tex]\begin{gathered} 86\text{chairs}=2\text{rows} \\ x=1 \\ 2\times x=86\times1 \\ 2x=86 \\ \end{gathered}[/tex]divide both sides by 2
[tex]\begin{gathered} \frac{2x}{2}=\frac{86}{2} \\ x=43 \end{gathered}[/tex]from the calculation above, we have 43 chairs in 1 row