Answer:
1. ‘cout’ was not declared in this scope.
2. ‘cin’ was not declared in this scope.
3. lvalue required as left operand of assignment.
Explanation:
The code gives the error cout and cin was not declare. This error means, we not include the library where they define.
cout and cin is the input/output instruction and they include in the library iostream file.
the last error is lvalue required as left operand of assignment.
lvalue means the assignable value, we actually do the wrong assignment.
number1 + number2 = sum;
here, sum is is the assignment variable. so, it must be in the right side of the '=' operator.
sum = number1 + number2 ;
Now, the above is correct. the value number1 plus number2 is assign to sum.