Coffe cost $12.00 per case and tea cost $ 8.00 per case. If an order comes in for a total of 250 cases for $ 2,600, what was the specific number of cases of tea?

Start by setting up two equations---using the given data---which incorporate the two unknowns.

Let C denote the number of coffee cases, and T the number of tea cases.

One of your equalities which comes straight from the provided info is for the total number of cases overall:

C + T = 250

Now you set up a second equation, again using C and T and the given info, to describe the situation regarding the total cost of the shipment.

With two equations in two unknowns, you're 90% home. A little substitution or elimination (whichever method your book discusses) will get you to the solution.