Respuesta :
Simply substitute the 7 in for c in the equation then solve...
17 - 2c =
17 - 2 (7) =
17 - 14 = 3
17 - 2c =
17 - 2 (7) =
17 - 14 = 3
17-2c for c=7
Replace c by its number
17-2(7)
17-14
= 3
I hope that's help !