(SAT PREP) FIND THE VALUE OF X PLEASE ASAP AWARDING BRAINLIEST!!

2men and 7 boys can do a piece of working 4 days.it is done by 4 men and 4 boys in 3 days how long would it take for 1man or one boy to do it alone

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?

7. the area of the playing surface at the olympic stadium in beijing isof a hectare. what area will it occupy on a plan drawn to a scaleof 1: 500?