Final answer:
An else if statement that prints 'goodbye' if a variable named userString is 'quit' can be written in a C-based programming language using the condition userString == 'quit' within the else if block of a conditional structure.
Step-by-step explanation:
To write an else if statement that prints 'goodbye' if userString is 'quit', you can use the following code structure, assuming the programming language is something like JavaScript or a C-based language:
if (condition) {
// code to execute if condition is true
} else if (userString == 'quit') {
console.log('goodbye');
} else {
// code to execute if no previous conditions are met
}
In this structure, if the variable userString equals the string 'quit', the program will output 'goodbye' to the console. It's important to note that the surrounding context for this else if statement may include other conditions and possibly a final else to handle any other cases.