Chapter 1-2 - Cumulative Review - Page 152: 13

$a=\dfrac{13}{18}$

Using the properties of equality, the solution to the given equation, $ 9(2a-1)=4 $, is \begin{array}{l}\require{cancel} 9(2a)+9(-1)=4 \\\\ 18a-9=4 \\\\ 18a=4+9 \\\\ 18a=13 \\\\ a=\dfrac{13}{18} .\end{array}