3.) r=2: 2+4/15= 6/15=2/5
2.) -3a-15=a: the fraction is negative. meaning the answer is negative, leaving a and c as choices. You can't square a since it is on different sides of the equation leaving you with c.
1.) answer is 5(x+4)=30: 3 is 2, meaning you would use the 2.
Answer: 4x^3+2x^2-12x+8
I am sorry it takes to long to type in the equation of this problem step by step. I only can just give you an answer.