How to Solve for a Variable

Solve for a Variable
••• d3 Dan @ flickr:

Solving for the variable in a math problem isn't as hard as some may think (thanks to the elimination method that is!) Here are step by step instructions of how it's done.

    The first thing you'll want to do is critique the problem. What are you being asked to solve for? Once you understand that you can move on.

    Let's say you're being asked to solve for y and the problem looks like this: 16x+4y=20. Basically what's being asked here is to get all the numbers on the other side of the equal sign so that y is by itself, i.e. y=(all the other things you've put on the other side of the equal sign).

    Begin by subtracting the number that's being added to 4y. In this case that number would be 16x (the variable, x, goes with it the number too, remember that) So after you've subtracted 16x your problem should look like this:


    Now you've made the problem a bit easier. It might look like you're done but ask yourself, "Is y totally by itself?" No it is not, there's a 4 clinging to it! So now we need to get 4 to the other side of the equal sign as well which will finally leave y by itself.

    What you'll need to do now is divide the 4 into both side of the equation. The 4/4 in front of the y's will cancel out and become 1y (at this point, the 1 turns invisible so that all you'll see is y, the one will always be there, but consider it invisible). So now all you have to do is divide 4 into 20+16x. You will get: y=5-4x

    And now your problem is solved. You've not only gotten all the other numbers to the other side of the equal sign, but you've reduced those numbers by dividing them by 4.

    Things You'll Need

    • Math problem with a variable in it.
    • pencil
    • papper

Related Articles

How to Solve for X
How to Subtract Mixed Numbers With Regrouping
How to Write the Remainder As a Whole Number
How to Solve Absolute Value Equations
How to Find The Square Root of a Number
How to Convert a Decimal to a Whole Number
Standard Form of a Linear Equation
How to Round Decimals
How to Factorise in Math
How to Multiply and Divide Mixed Fractions
How to Solve Inequalities With Fractions
How to Write a Repeating Decimal As a Fraction
How to Change Improper Fractions to Mixed Numbers or...
How to Simplify Fractions With Variables
How to Find Linear Functions
How to Simplify Rational Expressions: Step-by-Step
How to Factor Polynomials With 4 Terms
How to Simplify a Mixed Number
When Do You Flip the Inequality Sign?
How to Get the Value of a Letter in Algebra 1