Solve for x pls help me

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

What number line represents the solution set for the inequality -1/2 greater than or equal to 4

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?