Use elimination to solve the system:

$\displaystyle{x}+{4}{y}={29}\usepackage{cmbright}\Huge\$

$\displaystyle{5}{x}+{6}{y}={75}\usepackage{cmbright}\Huge\$

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