Find the value of 2 numbers if their sum is 24 and their difference is 4?

Simplify 4 square root of 2 end root plus 7 square root of 2 end root minus 3 square root of 2 . (1 point) 2 square root of 8 8 square root of 2 8 square root of 6 6 square root of 8

How do i do this? i don’t understand

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?