Answer:
 The expression  has two variables x and y.
 has two variables x and y. 
Step-by-step explanation:
<u>What is a variable?</u>
A variable is a letter, for instance  or
 or  , that represents an unknown number.
, that represents an unknown number.
Given the expression

The given expression has three terms which are x, 4y, and -9.
Here:
- The term 'x' is the unknown variable x.
- The term '4y' has a coefficient (the number next to a variable y) of 4.
- The term '-6' is a constant.
As we already know that a variable is a letter, for instance x or y, that represents an unknown number. In other words, the values of x, or y are unknown to us.
Thus, the expression  has two variables x and y.
 has two variables x and y.