Problem 1: Which of the followings are the valid variable names in C++? (a) 3x (6) xyz123 @)X2_0_7 (d) s%123 (c)X2_0_7 (d) s%123 (e) errM (f) d-00 (g) $x (h) #C (1) C++ G) C (k) M_{12} Problem 2: Which of the following are valid C++ statements? Assume that the variables i, x, and percent are already declared as int variables. Assume those variable are properly initialized at the beginning of the program. (c) x=x+x; (d) x = 3 +x; (e) percent = percent; (a) i=i+5; (b) x+2 = x; (f) x= -x; (g) -x= x