In one of my assignments I have one exercise, where I should solve the equations with more than one unknown without performing a single calculation: E.g.: $$x + 15.4y = 12.5$$ or $$a + 4.15b + 7.25c + 22.01d = 2.54$$
My solution for the first one: $$x = 12.5 - 15.14y$$ That means that the equation has infinite number of solutions and the solution are all pairs (x, y).
But what kind of solution is expected from me? How should I write that the solution are all the pairs mentioned above mathematically? This task has appeared in the matrix chapter, so I guess it has to do something with it. Thanks for help.