I think I might have found some answers, if someone could possibly verify them for me that would be great. Thanks

a) Variable cost per unit = 75,000+90,000+45,000+60,000/15,000

Therefore variable cost per unit = $18

b) Selling price = 43, VC per unit = 18, Contribution margin = 43-18 = 25

Target Net income = 25,000

Required sales = Fixed costs + Target Net income/CM per unit

= 70,000+25,000/25

= 3,800 units

c) 7500 units sold, profit of 30,000 after taxes, VC per unit = 18

First find the CM per unit

CM per unit = fixed costs + (target net income/1-tax rate)/units sold

= 70,000 + (30,000/.6)/7500

= 120,000/7500

= 16

Selling price = VC per unit + CM

= 18 + 16

= $34

d) Im still unsure about

Any verification and/or help would be awesome. Thanks