Answer:
In the given expression

Variables = m, r
Coefficients = 7, 6 and -3
constant= -8
Explanation:
We are given the expression

We need to give variable, coefficients and constant.
Variable: The value of variable may change. It can be represented by x, y or any other letter
Coefficients: A numerical or constant quality that is placed with the variable. For example in 4x, 4 is coefficient
Constant: It is fixed value. It cannot be changed.
So, in the given expression

Variables = m, r
Coefficients = 7, 6 and -3
constant= -8