Because he’s taxed by his home planet, Mork pays a tax rate of 40% on his income, while Mindy pays a rate of only 25% on hers. If Mindy earned 4 times as much as Mork did, what was their combined tax rate?  Select:  A) 28 %  B) 30 %  C) 32 %  D) 34 %  E) 36 %

Rationale: "let x be mork ' s income , then mindy ' s income is 4 x . the total tax paid is 0.4 x + 1.0 x = 1.4 x 1.4 x / 5 x = 0.28 the answer is a ."
Answer: A