Why can't my Java code see doubles from if statements? [duplicate]

I'm taking a class for java at my Highschool and I'm trying to complete an assignment. Everything is completed except for the fact that my code isn't reading the integers I made in my if statement. If anyone has some solutions, that would be greatly appreciated. If needed I can add my full code, but I believe this snippet should be enough.

if (letter == A) {
      double mAF = 1.0;
      double fAF = 1.0;
    } else if (letter == B) {
      double mAF = 1.3;
      double fAF = 1.3;
    } else if (letter == C) {
      double mAF = 1.6;
      double fAF = 1.5;
    } else if (letter == D) {
      double mAF = 1.7;
      double fAF = 1.6;
    } else if (letter == E) {
      double mAF = 2.1;
      double fAF = 1.9;
    } else if (letter == F) {
      double mAF = 2.4;
      double fAF = 2.2;
    } else {
      test--;
      double mAF = 0;
      double fAF = 0;
    }
    double mCal = mAF * BMR;//error here, cannot sense mAF
    double fCal = fAF * BMR;//error here, cannot sense fAF