var age = 20
print("I am \(20) years old, that's \(age * 7) in dog years.")
// I am 20 years old, that's 140 in dog years.

var lastName = "Gallaugher"
var phrase = "My last name is \(lastName) and it contains \(lastName.count) letters."
print(phrase)
// My last name is Gallaugher and it contains 10 letters.