A person with a one-bedroom apartment used x kWh of electricity one month and y kWh the next month. Since he used a lot of electricity the first month, he made an effort to use less the second month. The decrease in his usage, $\displaystyle{x}-{y}\usepackage{cmbright}\Huge\$ , was 58 kWh. His average usage for the two months, $\displaystyle\frac{{{x}+{y}}}{{2}}\usepackage{cmbright}\Huge\$ , was 323 kWh. How much electricity did he use during the second month? $\displaystyle{y}=\usepackage{cmbright}\Huge\$ _____ kWh