Solve Constraints
Constraints describe the limitations on the amount of resources available to optimize the objective function. In the Constraints panel, add whatever Constraints are applicable to the problem.
Click the + symbol to add a constraint, and the “clear constraints” button to remove all constraints:
Click on Name to give a name to the constraint.

Enter a cell reference in the first box, to represent the resource that is limited in this constraint. The cell is highlighted in the grid once specified.
If a range of cells is subject to the same constraint, you can enter that cell range here, rather than create a different constraint for each cell.

The relational operator can be >= (greater than or equal to), <= (less than or equal to), or = (exactly equal to). Choose one from the dropdown list.
A constraint such as 0 ≤ a16 ≤ 1000 must be expressed as two separate constraints: a16 >= 0 and a16 <= 1000.

Enter a quantity in the final box:
You can alternatively enter a cell reference here, or a range of cells, as in a. above, if that range of cells represents a set of similar constraints.
Note: The more constraints are added to the problem, the longer it might take to solve.
Examples
Flour <= 1000000 represents a constraint on a cooking ingredient with limited resources.

Pies >= 100 represents a minimum quantity that must be produced.

T = 40 represents the average time per week that a worker is available to work, where T is the number of hours.
