helooo!! i’m reviewing for a test and these type of questions are very confusing, can someone help explain?

How can you find the magnitude of a vector, v = < x,y > , where the horizontal change is x and the vertical change is y?

If a revenue in total for a month was $9,950, fixed expenses were $9,000, and variable expenses were $300 what would be the total profit/ loss for the month?

What is a correct first step in solving the inequality-4(3-5x)> -6x+9