When is it hard to show if a set is closed or not closed?

Asquare and an equilateral triangle have the same perimeter. each side the triangle is 4 inches longer than each side of the square. what is the perimeter of the square

In a young single person's monthly budget, $150 is spent on food, $175 is spent on housing, and $175 is spend on other items. suppose you drew a circle graph to represent this information, what percent of the graph represents housing?

You buy a veido game for $60 and the sales tax is 8% what is the total cost for the game including the sales tax