Answer:
double *average; // declaration of a doublе pointеr .
Explanation:
A pointer is a variable that will store the address of another variable of the same datatype. Here average is a pointer type variable that means it will store the address of double datatype variable.
syntax of declaring double datatype variable
double *variable_name ;
double *average;
For example:
double *average;
//declaration of a doublе pointеr
double r=90.897;
// variable r of double datatype
average=&r;// storing the address of r