You own a home and are thinking of doing some home repairs. This year there is a 50% tax credit on the cost of materials for adding insulation and for replacing windows and external doors. The maximum tax-credit is $3,000. a. You decide to add insulation to your attic which costs $1,200 in materials, and you install it yourself. What is the dollar amount of the tax credit? (Round your answer to 2 decimal places.) b. You are in a 25% tax bracket. How much does the home-repair tax credit reduce your tax liability? (Round your answer to 2 decimal places.) c. How much would you have to spend on qualified improvement materials to maximize your $3,000 tax credit?