The Turkish lira $($TL$)$ was officially devalued by the Turkish government in February $2001$ during a severe political and economic crisis. The Turkish government announced on February $21$ that the lira would be devalued by $20\%.$ The spot exchange rate on February $20$ was TL$67,00=$ $$1\mathrm{.}00.$ a$.$ What was the exchange rate after devaluation? b$.$ What was percentage change after falling to TL$96,000=$ $$1\mathrm{.}00?$