I don't understand how a typecast can sit at the beginning of a binary arithmetic expression. Does it typecast both variables or only one?

```
#include <stdio.h>
main()
{
    int sum = 17, count = 5;
    double mean = (double) sum / count;
    printf("Value of mean : %f\n", mean );
}

```

Is it casting `(double) (sum / count)` or only `((double) sum) / count`?