about c programming

Question

Sir, on which basis we have assigned the values for a & b?
eg.,int main() {
int a, b;
float salary = 56.23;
char letter = 'Z';
here bellow on which basis we have assigned the values to a and b
a = 8;
b = 34;
int c = a+b;

Answer 1

Randomly assigned values I assume ,

Answer 2

'Basis' what it means by you there? Can you explain more?