For part c) of this question, I calculated the contribution per unit to be 72.5, breakeven point in revenue to be 46206.9, and used the fixed cost figure of 20000.
Using the contribution to sales ratio method, I calculated the contribution per unit of 72.5, selling price per unit of 167.5, contribution to sales ratio of 0.432836, used the fixed cost figure of 20000 and calculated the breakeven point in revenue to be 46206.90.
Obviously your answer is wrong because it is different from the answer in the book. Apart from the fixed cost of $20,000 I have no idea where you are getting your figures from.