First solve the system for x and y.

$\displaystyle-{3}{y}+{8}{x}={18}\usepackage{cmbright}\Huge\$

$\displaystyle{y}={6}{x}-{6}\usepackage{cmbright}\Huge\$

The value of y that is part of the solution is $\displaystyle{y}=\usepackage{cmbright}\Huge\$ _____.