Respuesta :

JoyMark

Answer:

x = 12 m = 87

Step-by-step explanation:

x = Dave

(7x + 3) + x = 99

8x + 3 = 99

      -3     -3

8x = 96

----    ----

8       8

  x = 12

7(12) + 3

84 + 3

   87

Dave has 12 dollars, Martha has 87.