Solving for a Variable - Middle school math

Solve for t in the following equation:

3t + b = 5

When a problem asks to solve for a particular variable, it means to isolate that variable on one side of the equation (equal sign) and isolate the other terms on the other side of the equal sign.

In order to isolate the t term in the above problem, we must eliminate b from the left side of the equation. This can be accomplished if b is subtracted from both sides of the equal sign as follows:

3t + b – b = 5 – b

It is important to remember that whatever is done to the right side of the equation must be done to the left side also.

At this point b is eliminated from the right side of the equal sign and the resulting problem is:

3t = 5 – b

It is necessary at this time to eliminate the number 3 from the left side of the equation. There are two ways that may be used to accomplish this. Either multiply both side of the equation by (1/3) or divide both side of the equation by 3.

Lets divide each side by 3 as follows:

(3t) / 3 = (5 - b) / 3

The 3’s on the left side of the equation cancel out and the problem is finalized as follows:

t = (5 - b) / 3

©Copyright 2008.Najwa S. Hirn. All rights reserved.