Which property is this an example of?

At a local museum, the total price for one adult and one child is $11. mrs. smith paid for herself and her three children. she spent $19. record the system of equations to be solved and then find the price of an adult and child ticket using either elimination or substitution.

The table below shows the number of free throw shots attempted and the number of shots made for the five starting players on the basketball team during practice. each player's goal is to make 80% of her shots.

Arectangular lawn is 14m long and 10m wide. a strip of uniform width is mowed around the outside of the lawn. how wide is the strip when the area of the unmowed portion of the lawn is 12m². (the answer is 4m, but i need to know how to solve it)