how would I use the solver tool?

Hi Dipti, Thank you for the post and welcome to the forum, in answer to your question; Solver is activated from the Tools menu and choose Solver, the Dialog box will open offering you a number of choices;
Solver is a powerful optimisation and resource allocation tool, It can help you uncover the best uses of scarce resources so that desired goals, such as profit can be maximised, or undesired goals such as cost can be minimised. Solver answers questions such as:
1. What product price or promotion mix will maximise profit?
2. How can I live within the budget?
3. How fast can we grow without running out of cash?
Instead of guessing over and over, use Solver to find the best answer. When solving a problem with Solver you;
1. Specify the target cell that you want to minimise. maximise or set to a certain value.
2. Specify the changing cells that you want adjusted until a solution is found. You can specify up to 200 changing cells.
3. Specify constraint cells that must fall within certain limits or satisfy target values.
So, using Solver, you can find an optimal value for a formula in one cell, called the target cell on a worksheet.
Solver works with a group of cells that are related, either directly or indirectly to the formula in the target cell. Solver adjusts the values in the changing cells you specify, called the adjustable cells, to produce the result you specify from the target cell formula. You can apply constraints to restrict the values Solver can use in the model, and the constraints can refer to other cells that affect the target cells formula.
After solving the problem, you can create three types of report that summarise the results of a successful solution process.
When you save a Workbook, the last selections made in the Solver Parameters dialog box are retained for each worksheet on which you have defined a Solver problem. However, you can define more than one problem for a worksheet by saving them individually using the Save Model button in the Solver Options dialog box, you can then use the Load Model button to open a saved problem model.
You can also save the Solver settings for the problem as a scenario using the Scenario Manager.
Note: If Solver is not available on the Tools menu, choose the Tools>Add-Ins command and select the Solver check box.
I hope that has helped, if so please click the Resolved link, best regards Pete,
Pete Emmerson - Microsoft Office Specialist Master Instructor