Write a program that translates a letter grade into a number grade. letter grades are a, b, c, d, and f, possibly followed by + or –. their numeric values are 4, 3, 2, 1, and 0. there is no f+ or f–. a + increases the numeric value by 0.3, a – decreases it by 0.3. however, an a+ has value 4.0. enter a letter grade: bthe numeric value is 2.7. use a class grade with a method getnumericgrade.