What is the constant expression of 3m+7

The constant in an algebraic expression is the only term that cannot be changed.

Terms with variables are not constants as their values can changed as the variables change.

Our equation is 3m+7

M is a variable. Therefore the term '3m' is not the constant.

This leaves us with the term '7'. There is no variable present in this term.

'7' is the constant in this equation.