20) Give meaningful identifiers for the following variables and write a proper C++ declaration and initialization to a reasonable value. a) A variable to store the letter grade, (A, B, C, D, or F). b) A variable to store the sales tax price of an item. c) A variable to store the number of juice bottles sold. d) A variable to store the billing amount of a doctor's visit. e) A variable to store the grade point average (GPA). 24) The following program has syntax errors and/or the statements are in the incorrect order. Correct them. On each successive line, assume that any preceding error has been corrected. using namespace std; include int main() int numl; num2; string stri, cout > string cout