Answer
An income of 3 to 1 is most commonly preferred.
Work Step by Step
Order is important when writing a ratio. The quantity mentioned first is the numerator. The quantity mentioned second is the denominator.
An income of 1 to 3 means that you earn $3$ times less of what your friend earns.
An income of 3 to 1 means that you earn $3$ times more of what your friend earns.
