Right now you have £20. As well as using fixed numbers in calculations and storing the answer in a variable, we can also use variables within the calculations themselves. In this example ...

Dual variables are computed by solving the dual problem of the original linear programming problem ... that limits the amount of resources you can use, and the dual variable is positive, it ...

Some programming languages ... the memory used for all local variables is removed. In general, the use of global variables should be avoided wherever possible.