Is $x+2$x+2 an expression or an equation?
It is an expression.
It is an equation.
Is $6x$6x an expression or an equation?
Is $5k=15$5k=15 an expression or an equation?
Is $3-w$3−w an expression or an equation?
Simple linear equations in one variable (in contextual problems) with two operations (avoid complicated coefficients)