A numerical expression is a mathematical phrase that includes numbers and operations but no variables.

An algebraic expression is a mathematical phrase that includes numbers, variables, and operations.

The constant term is 5.

Combining like terms means to add or subtract terms that have the same variable raised to the same power.

The variable is r.

The result is 15.

A term is a single mathematical expression that can be a number, a variable, or a combination of both multiplied together.

The coefficient is 7.

A numerical expression contains only numbers and operations, while an algebraic expression contains numbers, variables, and operations.

Two terms are like if they have the same variable raised to the same power.