Use elimination to solve the system:

$\displaystyle{7}{x}-{7}{y}={21}\usepackage{cmbright}\Huge\$

$\displaystyle{2}{x}-{7}{y}={41}\usepackage{cmbright}\Huge\$

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