# How do you write a variable expression for the word phrase "the sum of 9 and a number"?

Jan 5, 2016

The most common letter used is $x$, but you won't find it strange when the variable comes as $y$, $a$, $b$, $t$... And it makes no difference!
If $x + 1 = 2$ and $y + 1 = 2$, what's the difference? None!
In this case, you can rename it as $9 + x$, using the most commonly used letter in the alphabet!