What is the role of protected access specifier in inheritance in C++?

Protected members are accessible in the class that defines them and in classes that inherit from that class.

What is the size (in bytes) of the character string declared below, char a[100];

The size of primitive data-type char in C programming is 1 byte. A declaration of form char a[n]; declares a string of size n, i.e. a string which can accomodate at most n characters. Looking at the string declaration in the question, we can see that the string 'a' can accomodate a maximum of 100 characters. So, the size of the variable 'a' is, 100*1 byte=100 bytes

Solve the equation for x, 4x+3=2x+5

Given equation is: 4x+3=2x+5 Subtracting 2x from both sides, 4x+3-2x=2x+5-2x 2x+3=5 Subtracting 3 from both sides, 2x+3-3=5-3 2x=2 Dividing both sides by 2, 2x/2=2/2 x=1