After landing a job in Wall Street, you have to decide how to weather the sudden thunderstorms

in New York. One solution is to buy now $20$ low$-$quality umbrellas for $$10$ each from a street$-$vendor;

they are useless after a thunderstorm, but this quantity is expected to get you through your first

year. Another option is to buy a very elegant, $$made in France$$ umbrella for $$170$ that will last

you for $2$ years. Finally, the famous Greek model $$Uranus$$ is available; it is the most expensive

one, priced at $$225,$ but it lasts for $3$ years. Having just graduated from college your credit score is

not exactly stellar, so your discount rate is $30\%.$

$1.$ Which umbrella model should you choose?