Respuesta :

setup a simple algebraic equation and solve.

5x = 7x-28

-5x   -5x

0=2x-28

+28  +28

28=2x

Now divide both sides by 2 and you get that she is 14

Answer:

14yrs

Step-by-step explanation:

Mary’s age=x

5•x = x•7-28

=> 5x-7x= -28

=> -2x= -28

=> x= -28/-2

=> x= 14