pls answer with formula

Pls answer with formula

please answer with formula, Thanks!!

Hot Buns, a specialty hamburger buns supplier, has offered to sell The Garden Griddle their hambuger buns for $.90 each. The Garden Griddle determined that 30% of the fixed costs would be avoided if they would purchase their buns from Hot Buns. If The Garden Griddle decides to accept the offer, what will the impact be on the company's profit? Flat Stitch needs three different pieces of material in order to produce one jersey. Currently the material is made by Flat Stitch. During the monh of March, Flat Stich produced 4,000 pieces of material. The recorded the following costs: The manufacturing overhead is made up of $1.00 per unit of variable overhead and $.30 of allocated fixed costs. Flat Stitch determined that they will need to supply 6,000 pieces of material for next years jerseys. Jersey Mike's has offered to sell Flat Stich the material that they need for their jerseys for $7 per unit. If Flat Stich decides to take Jersey Mike's offer, all of the variable costs, and $1200 of the fixed costs will be avoided. Should Flat Stitch accept the offer from Jersey Mike's? The computer center of Local Bank is considering purchasing a super computer. This computer comes with an investment cost of $150,000. The computer center expected to get an annual net cash flow of $20,000 per year from this new computer. Calculate the payback period