Please show all of the work for the whole question. (Previous expert did not do so)

Three Little Pigs Co. makes playhouses and tree houses for children. For playhouses, the price is $120 and variable expenses are $90 per unit. For tree houses, the price is $200 and variable expenses are $100. Total fixed expenses are $253,750. Last year, Three Little Pigs sold 12,000 playhouses and 4,000 tree houses. What is the sales mix of playhouses to tree houses? Three Little Pigs expects tree house demand to increase from 4,000 to 8,000 units. By how much does the contribution margin change with this increased demand? By how much does profit change with this increased demand? If Three Little Pigs desires to earn an operating income of $90,000 how many of each product (playhouses and tree houses) must they sell