Nicholas decided to take a hot air ballon ride. after being in the air for 20 seconds, he is 200 feet above the ground. after being in the air for 60 second, he is 400 feet above the ground. what is his rate of ascent in feet per second?

Bismuth-210 is an isotope that radioactively decays by about 13% each day, meaning 13% of the remaining bismuth-210 transforms into another atom (polonium-210 in this case) each day. if you begin with 233 mg of bismuth-210, how much remains after 8 days?

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?

Ntriangle abc, m∠a = 35° and m∠b = 40°, and a=9. which equation should you solve to find b?