The function that adds them is given by: In the file that contains the int main ():

```
add(m1,m2, sum);
cout << "The sum is:";
sum.display_money();
```

In the .h file:

```
friend void add(AltMoney m1, AltMoney m2, AltMoney& sum);
```

In the .cpp file

```
void add(AltMoney m1, AltMoney m2, AltMoney& sum)
{
int extra = 0;
sum.cents = m1.cents + m2.cents;
if(sum.cents >=100){
sum.cents = sum.cents - 100;
extra = 1;
}
sum.dollars = m1.dollars + m2.dollars + extra;
}
```

From that implementation I want to subtract one from the other ...

The sum I am calling by reference, but I can not find the logic to subtract.

Thanks for your time and help.