a=2
Explanation
[tex]18=4a+10[/tex]Step 1
subtract 10 in both sides
[tex]\begin{gathered} 18=4a+10 \\ 18-10=4a+10-10 \\ 8=4a \end{gathered}[/tex]Step 2
divide each side by 4
[tex]\begin{gathered} 8=4a \\ \frac{8}{4}=\frac{4a}{4} \\ 2=a \\ a=2 \end{gathered}[/tex]