A equation is any expression that you can answer and find the "x" or another letter.
Whereas a<span></span>formula<span> is a set of instructions for creating a desired result. This is a kind or explanation in which you show how to resolve the equation.
It is 3 because fi you multiply 5 by 3 you get 15, and if you multiply 10 by 3 you get 30. Subtract 30 by 6 and get 24. And finally, if you multiply 2 by 3 it gives you 9. 9+12= 21.
We can solve inequalities to find all values of the variable that make the inequality true. The idea is to get the variable all by itself on one side of the inequality sign so we can easily see the solutions to the inequality.
Hence for any given inequality and for any given number if we put that number in that inequality and see that the given inequality sign holds true than that number will be a solution of the inequality otherwise it is not an solution of the inequality.