Write 20.5×10^-5 in standard form. please help​

Asegment in the complex plane has a midpoint at 7 – 2i. if the segment has an endpoint at 11 – 3i, what is the other endpoint?

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

Hector and alex traded video games. alex gave hector one fourth of his video games in exchange for 6 video games. then he sold 3 video games and gave 2 video games to his brother. alex ended up with 16 video games. how many video games did alex have when he started?