Each interior angle of a regular polygon measures 90.
How many sides does the polygon have?

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

Write the equation in general quadratic form: plz !