In the options given below, there are a few terms picked from an algebraic expression in x and y.
Which of them is a constant?
7
A constant is a number on its own which has a fixed value whose value does not change.
In the given options the values of 'xy', '4x+6y' and 'pxy' are not fixed and can change depending on which value 'x' and 'y' takes, but '7' is a fixed value.
So '7' is a constant and others are variables.