## Solutions

### 4. Variables

#### Exercise 2:

```#include <iostream>
using namespace std;
int main()
{
cout << "Type in the price: " << endl;
double price=0;
cin >> price;
double discount = 0.1*price;
cout << "After a 10% discount: " << price - discount << endl;
}
```

#### Exercise 3:

```#include <iostream>
using namespace std;

int main()
{
cout << "Type in the price before discount: " << endl;
double priceA=0;
cin >> priceA;

cout << "Type in the price after discount: " << endl;
double priceB=0;
cin >> priceB;

double discount = 1 - priceB/priceA;
cout << "The discount rate is: " << discount*100 << "%" << endl;
}
```

#### Exercise 4:

```#include <iostream>
using namespace std;

int main()
{
cout << "Type in the length of a movie in hours and minutes."
<< endl;
cout << "You can put each number in its own line or separate"
<< endl;
cout << "the numbers by a space." << endl;
double hours=0;
cin >> hours;
double minutes=0;
cin >> minutes;

double timeInMinutes = hours*60 + minutes;
cout << "The length is " << timeInMinutes << " minutes." << endl;
}
```

#### Exercise 5:

```#include <iostream>
using namespace std;

int main()
{
cout << "Enter the length of a movie in hours, "
<< "minutes and seconds:" << endl;
double hours=0;
cin >> hours;
double minutes=0;
cin >> minutes;
double seconds=0;
cin >> seconds;

double timeInMinutes = hours*60 + minutes;
double timeInSeconds = timeInMinutes*60 + seconds;
cout << "The length is " << timeInSeconds << " seconds." << endl;
}
```