There are many excellent online resources for learning about and solving equations.
Note that WolframAlpha is excellent for checking solutions to equations.

Note that you can change the equations inside the above widgets.
Alternatively – just type your equation into WolframAlpha.
(Note that step by step solutions are for pro subscribers but you can get answers to as many equations as you want, so WolframAlpha is great for checking work).

Mathisfun has a very easy to use Quadratic Equation Solversimply enter the coefficients (a, b and c) and the solutions and a graph will be returned.

Try this calculator from Math Warehouse which shows the working very clearly using the formula.

Quadratic Equation Calculator – Math Wareouse

For practising solving linear equations Duncan Keith’s excellent linear equation calculator is excellent. The Subtangent resources from Duncan Keith are available from the National Stem Centre (the original site is no longer available).

The slideshow below shows how to use the calculator to solve equations where the unknown is on both sides.

Centre for Innovation in Mathematics Teaching
CIMT have tutorials on equations: Linear Equations 1Linear Equations 2and Linear Equations with Brackets in their Interactive Resources

The next two recommendations both require Java. Note – just in case you try any sites requiring Java and get a Java not detected message or other error message even though you have an up to date version of Java installed then the solution is here (scroll right down to Owen Holt’s comment and Screenr recording). Basically you need to Configure Java (see your programs list) and under the Security tab add an exception site, eg: http://www.fi.uu.nl/ I left my security setting as high and this did solve the problem.

NLVM – Equations

From the National Library of Virtual Manipulatives try Algebra Balance Scales and Algebra Balance Scales – Negatives.
Note that these manipulatives allow you to create a problem of your own (so long as it has an integer solution) as well as solving problems given.

One of the excellent Wisweb applets is Solving equations with balance strategy.
The solution is checked at each stage.
As well as solving the given problems (20 problems) the user can select ‘Make an equation yourself’ to enter any equation then solve that equation.
(Unlike the NLVM resource above the x can be any real number).

The following video shows the keystrokes required to enter and solve an equation.