When adding or subtracting two equations causes the coefficient to result 0 the variable is said to be

Elimination (also called add-subtract): This method involves adding the two equations together — or multiples of the two equations — so that in the sum, the coefficient of one of the variables becomes 0. That variable drops out (is eliminated), so you can solve for the other variable.

step-by-step explanation:

let m = monomial

let t = trinomial

so, m times t = t.

monomial times a trinomial = another trinomial.